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Structures, properties and applications of multifunctional lignin nanofibres Li, Yingjie 2015

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    STRUCTURES, PROPERTIES AND APPLICATIONS OF MULTIFUNCTIONAL LIGNIN NANOFIBRES by  Yingjie Li   A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in  THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Materials Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) July, 2015 © Yingjie Li, 2015        ii  Abstract This study explored the feasibility of creating multifunctional lignin materials in nanofibre form to establish a material platform for the development of value-added products. Specifically, softwood kraft lignin was electrospun, thermostabilized and carbonized into carbon nanofibres. Subsequently, functionalization of lignin based carbon nanofibres were conducted by (1) designing lignin-based composite carbon nanofibre; (2) preparing architecturally-designed lignin-based nanofibres and (3) preparing architecturally-designed lignin-based composite nanofibres. Examples of the advanced applications of the functionalized lignin based nanofibres were demonstrated such as electromagnetic interference shielding, energy storage and actuator. Flexible composite carbon nanofibres were embedded with functional fillers e.g. flexible electromagnetic lignin carbon nanofibres embedded with magnetic nanoparticles was developed. The amorphous structure of lignin and the addition of functional fillers impart the mechanical flexibility to lignin carbon nanofibre mats. By combining the magnetic permeability of magnetic nanoparticles and the electrical conductivity of lignin carbon nanofibre, flexible multifunctional lignin composite carbon nanofibres were created. Electromagnetic shielding effectiveness (SE) of lignin-based carbon nanofibres was comparable to that of the petroleum-based (such as polyacrylonitrile (PAN)-based) nanofibres.   The feasibility of using above flexible composite carbon nanofibres from lignin as the lithium ion battery anode was demonstrated. This anode is free-standing, binder-free and mechanically flexible mats. Using lignin nanofibres electrodes and solid electrolytes, flexible solid-state lithium ion batteries were successfully assembled and characterized.        iii  Moreover, functions were added to electrospun lignin nanofibres by developing architecturally-designed lignin based thermostabilized nanofibres. A unique actuating phenomenon in thermostabilized lignin nanofibres was observed. It exhibits fast, reversible and dramatic mechanical deformation and recovery in response to environmental moisture gradient at milliseconds level. The actuation mechanism was investigated at the molecular level, and fibre assembly level.  In summary, this study demonstrated that renewable biomaterials such as lignin has the potential for adding value through multifunctionalization in nanofibres form, thus creating a promising material platform for petroleum free feedstock for advanced applications.          iv  Preface A version of Chapter 4.4.1 has been published in Proceedings of SAMPE 2013 (Y. Li, A. Mei, D.G. Michelson, J. Kadla, and F. Ko, “Lignin-based Composite Nanofibres for Electromagnetic Interference Shielding” in Society for the Advancement of Material and Process Engineering (SAMPE) Conference, Long Beach, CA, 2013). I conducted all of the experiments and data analysis, and wrote the manuscript. Professors Frank Ko and John Kadla suggested corrections to improve the manuscript. Dr. Saeid Soltanian helped to conduct the bending test of the flexible carbon nanofibre mats. Mr Yu Wang helped to assemble the flexible solid state batteries.  I conducted the rest of the experimental work and wrote the entire manuscript.          v  Table of Contents  Abstract .................................................................................................................................................... ii Preface ..................................................................................................................................................... iv Table of Contents ..................................................................................................................................... v List of Tables ........................................................................................................................................... ix List of Figures........................................................................................................................................... x List of Abbreviations .............................................................................................................................. xx Acknowledgements .............................................................................................................................. xxii Dedication............................................................................................................................................ xxiv Chapter 1 : Introduction ............................................................................................................................ 1 Chapter 2 : Literature Review .................................................................................................................. 6 2.1 Lignin ......................................................................................................................... 6 2.2 Carbon Fibre............................................................................................................... 7 2.2.1 Spinning .................................................................................................................. 9 2.2.2 Heat Treatment ..................................................................................................... 12 2.2.3 Mechanical Properties ........................................................................................... 12 2.3 Carbon Fibre from Lignin ........................................................................................ 13 2.4 Electrospinning of Lignin ........................................................................................ 14 2.5 Multifunctional Nanofibre ....................................................................................... 16 2.5.1 Functions Added at the Molecular Level .............................................................. 16 2.5.2 Functions Added at the Fibre Level ...................................................................... 17 2.5.3 Functions Added at the Assembly Level .............................................................. 19 2.6 Applications of Multifunctional Nanofibre .............................................................. 20       vi  2.6.1 EMI Shielding Application ................................................................................... 20 2.6.2 Application to LIB Batteries Electrodes ............................................................... 23 2.6.3 Application to Actuator......................................................................................... 28 Chapter 3 : Scope and Objectives ........................................................................................................... 30 Chapter 4 : Fabrication and Characterization of Multifunctional Lignin Nanofibre .............................. 33 4.1 Introduction .............................................................................................................. 33 4.2 Materials ................................................................................................................... 35 4.3 Methods .................................................................................................................... 35 4.3.1 Lignin Fractionation.............................................................................................. 35 4.3.2 Fabrication of Lignin-based Electrospun fibres .................................................... 36 4.3.3 Characterization of Lignin Nanofibres ................................................................. 38 4.4 Results and Discussions ........................................................................................... 41 4.4.1 Composite Carbon Nanofibre from Lignin ........................................................... 41 4.4.2 Architecture-designed Nanofibre from Lignin ..................................................... 69 4.4.3 Architecture-designed Composite Nanofibre from Lignin ................................... 79 4.5 Conclusions .............................................................................................................. 86 Chapter 5 : Flexible Lignin Carbon Nanofibre Application for EMI Shielding ..................................... 88 5.1 Introduction .............................................................................................................. 88 5.2 Materials and Methods ............................................................................................. 88 5.2.1 Materials ............................................................................................................... 88 5.2.2 EMI Shielding Test ............................................................................................... 89 5.2.3 Complex Permittivity Test .................................................................................... 90 5.3 Results and Discussions ........................................................................................... 90 5.3.1 EMI Shielding Test ............................................................................................... 90       vii  5.3.2 Shielding Mechanism............................................................................................ 93 5.3.3 Complex Permittivity ............................................................................................ 94 5.4 Conclusions .............................................................................................................. 97 Chapter 6 : Lignin Carbon Nanofibre for Flexible Lithium Ion Battery Application ............................ 98 6.1 Introduction .............................................................................................................. 98 6.2 Materials and Methods ........................................................................................... 100 6.2.1 Materials ............................................................................................................. 100 6.2.2 Methods .............................................................................................................. 100 6.3 Results and Discussions ......................................................................................... 101 6.3.1 Fabrication of Flexible LIB Anode from Lignin ................................................ 101 6.3.2 Integration of the Flexible Lignin Anode and Gummy Electrolyte .................... 103 6.3.3 Flexile Battery Assembly and Testing ................................................................ 105 6.4 Conclusions ............................................................................................................ 106 Chapter 7 : Lignin-based, Moisture-driven Actuator ........................................................................... 107 7.1 Introduction ............................................................................................................ 107 7.2 Materials and Methods ........................................................................................... 107 7.3 Results and Discussions ......................................................................................... 107 7.3.1 Actuating Phenomenon ....................................................................................... 107 7.3.2 Investigation of Movement Mechanism ............................................................. 112 7.4 Conclusion ............................................................................................................. 117 Chapter 8 : Conclusions and Future Directions .................................................................................... 119 8.1 Conclusions ............................................................................................................ 119 8.2 Future Directions .................................................................................................... 122 References ............................................................................................................................................ 125       viii  Appendix .............................................................................................................................................. 152          ix  List of Tables Table 2-1 Comparison between conventional Li-ion rechargeable battery and solid state battery133 ....................................................................................................................................... 25 Table 4-1  The intensity ratio (ID/IG), as well as the full width at half maximum (FWHM), and position 3% and 10% IAA/lignin-based composite carbon nanofibre carbonized at 700, 800, 900 and 1000 ˚C. .................................................................................................................................. 59 Table 4-2 Ms, Mr, Hc and average particle size of 3% and 10% IAA/lignin-based composite carbon nanofibres carbonized at 700, 800, 900 and 1000 ˚C (250-1-60) ..................................... 65 Table A-1 Functional group frequency and integration regions used for the quantitative 1HNMR spectra of lignin acetates ............................................................................................................. 155 Table A-2 The calculated amount of the phenolic hydroxyl group and aliphatic hydroxyl group from NMR ................................................................................................................................... 155                 x  List of Figures Figure 2-1 Three monolignol monomer structures and an example of a possible corresponding lignin structure 22(1:p-coumaryl alcohol, 2: coniferyl alcohol and 3:sinapyl alcohol) ..... 6 Figure 2-2 Chemical structure of PAN ........................................................................................... 9 Figure 2-3 Chemical structure of pitch 15 ..................................................................................... 10 Figure 2-4 The processing sequence for PAN (a) and mesophase-pitch-based precursor fibers (b) shows similarities for the two processes. Highly oriented polymer molecular chains are obtained in PAN by hot stretching, while high orientation in pitch is a natural consequence of the mesophase (liquid crystalline) order 31 ......................................................................................... 11 Figure 2-5 EMI Shielding mechanisms 116 ................................................................................... 23 Figure 2-6 Variation of reversible capacities (rate capability) for nanofibre webs thermally treated at 700, 1000, and 2800 °C at discharge current densities of 30, 50, and 100 mA/g, respectively134  (Reproduced with permission from John Wiley and Sons, Inc. ) ........................ 27 Figure 2-7 Cycle performances with C-rate of untreated natural graphite and Al-treated natural graphite sample. The circle, triangle, and rectangular plot represent 0.2 C, 0.5 C, and 1.0 C rate, respectively. The simple plot and bold one show untreated and treated samples, respectively. (a) Treated 0.2 C, (b) Treated 0.5 C, (c) Treated 1.0 C, (d) Untreated 0.2 C, (e) Untreated 0.5 C, and (f) Untreated 1.0 C 136 (Reproduced with permission from the Electrochemical Society (ECS).) 28 Figure 4-1 Softwood kraft lignin fractionation process150 ............................................................ 36 Figure 4-2 the custom-made device for bending test .................................................................... 40 Figure 4-3 SEM image of F4 as-spun nanofibre obtained from F4 solutions with different concentrations (a) 25%, (b) 30% and (c) 35% .............................................................................. 42       xi  Figure 4-4 SEM images of electrospun fibres obtained from F4 solutions containing 3% IAA with different lignin concentrations: (a) 25%, (b) 30% and (c) 35% ............................................ 42 Figure 4-5 SEM images of electrospun fibres from 35% F4 solutions with different IAA loadings amount: (a) 0%, (b) 1 %, (c) 3 %, (d) 5%, (e) 10 % and (f) 20% ................................................. 43 Figure 4-6 SEM images of thermostabilized lignin electrospun fibres from 35% F4 solutions with 3% IAA with heating rats of (a)  1 ˚C/min, (b) 3 ˚C/min and (c) 5˚C/min to 250˚C for 60 min .. 44 Figure 4-7 SEM images of thermostabilized lignin electrospun fibres 35% F4 solutions with (a) 0 %, (b) 1 %, (c) 3 %, (d) 5 %, (e) 10 % and (f) 20% IAA  treated with a heating rate of 5˚C/min to 250˚C for 60 min ........................................................................................................................... 45 Figure 4-8 SEM images of thermostabilized lignin electrospun fibres 35% F4 solutions with (a) 0 %, (b) 1 %, (c) 3 %, (d) 5 %, (e) 10 % and (f) 20% IAA  treated with a heating rate of 1˚C/min to 250˚C for 60 min ........................................................................................................................... 46 Figure 4-9 Typical SEM and TEM images of lignin carbon nanofibre (carbonized at 1000˚C) from F4 without IAA (a, b) and lignin composite carbon nanofibre from F4 with 3% IAA (c, d) 47 Figure 4-10 Effect of thermostabilization  and carbonization process on fibre diameter of 3% IAA/lignin-based composite carbon nanofibres carbonized at 700, 800, 900 and 1000 ˚C (thermostabilized at 250˚C, with ramping rate of 1˚C/min, and held for 60min) ......................... 48 Figure 4-11 Effect of carbonization temperature on particle size of 3% and 10% IAA/lignin-based composite carbon nanofibres carbonized at 700, 800, 900 and 1000 ˚C (thermostabilized at 250˚C, with ramping rate of 1˚C/min, and held for 60min).......................................................... 48       xii  Figure 4-12 Representative HRTEM images of core-shell nanopartiess obtained by in-situ synthesis method within lignin carbon nanofibre prepared from 1% IAA/35%F4, thermostabilized with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ....................................................... 49 Figure 4-13 (a) Representative STEM-HAADF image and EDX mapping of  (b) carbon, (c) iron, (d) oxygen and (e) sulfur of lignin electrospun carbon nanofibre prepared from 1% IAA/35%F4, thermostabilized with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ........................... 50 Figure 4-14 Representative XPS spectra of electrospun carbon nanofibre with 20% IAA thermostabilized with 5˚C/min and carbonized at 1000˚C: (a) survey (b) Fe 2p ......................... 51 Figure 4-15 XRD pattern of CNF obtained from electrospun fibres with different amount of IAA (1, 3, 5, 10 and 20%) with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C .................... 54 Figure 4-16 XRD pattern of CNF obtained from electrospun fibres with different amount of IAA (1, 3, 5, 10 and 20%) with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C .................... 55 Figure 4-17 XRD pattern of CNF obtained from electrospun fibres with 3% IAA with thermostabilization  heating rate of 1, 3 and 5˚C/min at 250˚C for 60min and carbonized at 1000˚C........................................................................................................................................... 55 Figure 4-18 Raman spectra of 3% and 10% IAA/lignin-based composite carbon nanofibres carbonized at 700,  800,  900 and 1000 ˚C (thermostabilized conditions : 1˚C/min, 250˚C and 60 min) ............................................................................................................................................... 56 Figure 4-19 Thermogravimetric analysis of thermostabilized electrospun fibres with different amount of iron salt (0, 1, 3, 5, 10 and 20%) with a heating rate of 1 ˚C/min to 250 ˚C for 60 min....................................................................................................................................................... 60       xiii  Figure 4-20 Derivative of weight loss as a function of temperature for thermostabilized electrospun fibres with different amount of iron salt ( 0, 1, 3, 5, 10 and 20%) with a heating rate of  1˚C/min to 250 ˚C  for 60 min ................................................................................................. 61 Figure 4-21 Thermogravimetric analysis of thermostabilized electrospun fibres with different amount of iron salt ( 0, 1, 3, 5, 10 and 20%) with a heating rate of  5˚C/min .............................. 62 Figure 4-22 Derivative of weight loss as a function of temperature for thermostabilized electrospun fibres with different amount of iron salt (0, 1, 3, 5, 10 and 20%) with a heating rate of 5˚C/min ..................................................................................................................................... 63 Figure 4-23 Representative magnetic hysteresis loops of 3% and 10% IAA/lignin-based composite carbon nanofibre carbonized at 700, 800, 900 and 1000 ˚C (Inset graph: enlarged range of the magnetic field from -250G to 250G ) ....................................................................... 64 Figure 4-24 Representative photos of (a) non-flexible carbon nanofibre mats and (b) flexible lignin carbon nanofibre mats with IAA. ....................................................................................... 67 Figure 4-25 Resistance change in the process of bending test for the flexible lignin composite carbon nanofibre with different IAA loadings (1, 3, 5, 10and 20%) ............................................ 68 Figure 4-26 SEM images of as-spun nanofibres from (a) 30% and (b) 35% solutions of F1-3 ..... 70 Figure 4-27 SEM image of as-spun nanofibres from the 30% solution of the blend of F4 F1-3 (weight ratio 5:5)........................................................................................................................... 70 Figure 4-28 Representative SEM images of the surface (a, c) and cross-section (b, d) of the nanofibre mat with the 3-D interconnected architecture (a, b electrospun from 30% solution of F4 and thermalized with 5˚C/min at 250˚C for 60 minutes; c, d electrospun from 30% solution of F1-3/F4 (F1-3:F4 =3:7) and thermalized with 5˚C/min at 250˚C for 60 minutes) ................................. 72       xiv  Figure 4-29 SEM images of thermostabilized nanofibre (5˚C/min, 250˚C, 60 minutes) from the blend of F4 and actylated-F4 with different blend ratios: (a) 7:3 and (b) 5:5 ................................ 73 Figure 4-30 SEM images of thermostabilized fibres from 30% solutions containing (a) F4, (b) F4:F1-3 =7:3, (c) F4:F1-3 =6:4 and (d) F4:F1-3 =5:5 with a heating rate of 5˚C/min to 250˚C for 1 hour ............................................................................................................................................... 74 Figure 4-31 SEM images of carbonized architecture-designed nanofibres (250˚C-5˚C/min-60 min) from 30% lignin solutions (F4:F1-3=5:5) at (a) 400 ˚C (b) 500 ˚C and (c) 600˚C ................ 75 Figure 4-32 SEM images of carbonized architecture-designed nanofibres (250˚C-5˚C/min-60 min) from 30% lignin solutions (F4:F1-3=7:3) at (a) 900 ˚C and (b) 1000˚C ................................ 76 Figure 4-33 TGA plots of thermostabilized fibres from F4 and the blend of F4/F1-3 with different ratios (7:3, 6:4 and 5:5) ................................................................................................................. 77 Figure 4-34 Electrical conductivity of non-bonded lignin carbon nanofibres sample 1 (spun from 30%F4 and carbonized at 900 ˚C) and inter-bonded lignin carbon nanofibres sample 2 (spun from 30%F4/F1-3 and carbonized at 900 ˚C) and sample 3 (spun from 30%F4/F1-3 and carbonized at 1000 ˚C) ........................................................................................................................................ 78 Figure 4-35 SEM images of electrospun fibres from the blending system of IAA-F1-3-F4 (a) 0%IAA-35% F4 /F1-3 (5:5), (b) 3%IAA-35% F4 /F1-3 (5:5), and (c) 3%IAA-40% F4 /F1-3 (5:5) ..... 80 Figure 4-36 SEM images of carbon nanofibres spun from the blending system of IAA-F1-3-F4 (a) 3%IAA-40% F4 /F1-3 (2:8), and (b) 3%IAA-40% F4 /F1-3 (3:7) and thermostabilized with 5˚C/min and carbonized  at 1000˚C ............................................................................................................ 81       xv  Figure 4-37 TGA plot of thermostabilized fibres (thermostabilized with 5˚C/min at 250 ˚C for 60 min) from the blending system of IAA-F1-3-F4: 3%IAA- F4 /F1-3 (2:8), 3%IAA- F4 /F1-3 (5:5), 3%IAA- F4 /F1-3 (6:4) and 0%IAA- F4 /F1-3 (10:0) ........................................................................ 81 Figure 4-38 SEM images of electrospun fibres from solutions of (a) 30% F4-3% Fe3O4, (b) 35% F4-3% Fe3O4, (c) 35% F4-5% Fe3O4 and (d)35% F4-7% Fe3O4 ..................................................... 83 Figure 4-39 SEM images of thermostabilized fibres with a heating rate of 5˚C/min from (a) 35% F4-3% Fe3O4 and (b)  35% F4-5% Fe3O4....................................................................................... 83 Figure 4-40 SEM images of thermostabilized fibres with a heating rate of 1˚C/min from 35% F4-3% Fe3O4 and 35% F4-5% Fe3O4 .................................................................................................. 84 Figure 4-41 TGA plot of thermostabilized fibres (250˚C-5˚C/min-60min) from the sonication system of 35% lignin solutions with 0% Fe3O4, 3% Fe3O4, and 5% Fe3O4 .................................. 85 Figure 5-1 Schematic of the measurement of complex permittivity162 (VNA denotes the vector network analyzer).......................................................................................................................... 90 Figure 5-2 Typical EMI SE results for the magnetic lignin carbon nanofibre/PDMS composites in the frequency range of (a) 10 MHz-18 GHz and (b)  10 MHz -3 GHz .................................... 91 Figure 5-3 Comparison of EMI SE (1-3 GHz) between the lignin-based magnetic carbon nanofibres and published data  (at 1GHz) ..................................................................................... 92 Figure 5-4 Comparison of EMI SE (8-12 GHz) between the lignin-based magnetic carbon nanofibres and published results ................................................................................................... 92 Figure 5-5 Typical SET, SER and SEA of (a) 3A900, (b) 3A1000, (c) 10A900,  and (d) 10A1000 (250-1-60) in the frequency range (8~12 GHz) ............................................................................ 94       xvi  Figure 5-6 (a) Real part and (b) imagery part of complex permittivity for samples (3% IAA, carbonization temperature 900˚C) with different carbon fibre content (4.4 wt. % and 7.5wt. %) 95 Figure 5-7 Complex permittivity results comparison between experimental results and published data ................................................................................................................................................ 96 Figure 6-1 Schematic of the fabrication process of the flexible battery ..................................... 101 Figure 6-2 SEM images of three types of LIB electrodes from lignin carbon nanofibres as (a) non-interconnected electrode (CNF from F4 thermalstablized at 5 ˚C/min, and carbonized at1000˚C), (b) 3-D interconnected electrode (7:3 F4:F1-3 , thermalstablized at 1C/min, and carbonized at1000˚C), and (c) flexible electrode (3%IAA, thermalstablized at 1C/min, and carbonized at1000˚C) .................................................................................................................. 102 Figure 6-3 The charge/discharge curves of carbon nanofibre electrode from lignin (black line: 1st cycle, red line: 2nd cycle, and blue line: 3rd cycle): (a) non-interconnected,(b) 3-D interconnected, and (c) flexible electrode. ........................................................................................................... 103 Figure 6-4 SEM image of the cross-section of the flexible lignin electrode integrated with the gummy electrolyte ...................................................................................................................... 104 Figure 6-5  Contact angle measurement (a) gummy electrolyte on commercial graphite anode and (b) gummy electrolyte on flexible lignin carbon nanofibre electrode; (c) dynamic changes of the contact angles ........................................................................................................................ 105 Figure 6-6 Battery charge and discharge cycling test ................................................................. 106 Figure 7-1 High speed camera photo of the fast actuation responses of lignin actuator on moisture substrate: (a-b) contraction and expansion motion and (c-e) rotation motion ............. 108       xvii  Figure 7-2 Locomotion of a lignin actuator film on a moist substrate (1): asymmetric swelling the curling away from the substrate (2); the contact surface area decreased and the film’s center of gravity rose, leading to mechanical instability (2); the buckling and toppling of the film (3); the actuator rolled up into a carpet (4);  the film fell back to the substrate with a new face down (5) to start a new cycle. ............................................................................................................... 110 Figure 7-3 Correlation between fibre morphology and response (a, b) non-responsive to water, and (c,d) responsive to water vapor (scale bar 10 um) ............................................................... 113 Figure 7-4 FT-IR spectra of thermostabilized fibres from F4: F1-3 (5:5) and the carbonized nanofibres at 400, 500 and 600˚C ............................................................................................... 114 Figure 7-5 Actuation mechanism of lignin actuator ................................................................... 116 Figure A-1 Comparison of 24 hours acetylation and 48 hours acetylation for F4 ...................... 153 Figure A-2 24hours acetylation F4 1H-NMR for OH calculation............................................... 153 Figure A-3 48hours acetylation F4 1H-NMR for OH calculation............................................... 154 Figure A-4 SEM and TEM images of 10A 35 carbonized electrospun fibres obtained at different temperature 900 and 1000 ˚C (10A35F4-250-1-60) ................................................................... 156 Figure A-5 SEM and TEM images of carbon nanofibre electrospun from solutions of 3%IAA/35%F4, thermostabilized at 250˚C with heating rate of 1˚C/min, carbonized at 700 (3A700) (a,b), 800 (3A800) (c,d), 900 (3A900) (e,f) and 1000 ˚C (3A1000) (g,h) ................... 157 Figure A-6 SEM and TEM images of carbon nanofibre electrospun from solutions of F4, thermolstablized at 250˚C with heating rate of 1˚C/min, carbonized at 1000˚C with different IAA concentration,1% (a,b), 3% (c,d), 5%(e,f), 10% (g,h)  and 20% (i,j) ......................................... 159      xviii  Figure A-7 SEM and TEM images of carbon nanofibre electrospun from solutions of F4, thermolstablized at 250˚C with heating rate of 5˚C/min, carbonized at 1000˚C with different IAA concentration,1% (a,b), 3% (c,d), 5%(e,f), 10% (g,h)  and 20% (i,j) ......................................... 160 Figure A-8 SEM images of composite carbon nanofibre (1000˚C) from solution of 3%IAA/35%F4 with different thermostabilization  heating rate:(a) 1 ˚C/min, (b) 3 ˚C/min and (c) 5 ˚C/min ...................................................................................................................................... 161 Figure A-9 Representative STEM-HAADF image of lignin carbon nanofibre (10A35F4-250-1-60-1000-10-60) with the in-situ synthesized nanoparticles and mapping of carbon, iron and oxygen ......................................................................................................................................... 162 Figure A-10 Representative TEM images of lignin carbon nanofibre with the in-situ synthesized nanoparticles 20A35F4-250-5-60-1000-10-60 ........................................................................... 163 Figure A-11 Representative STEM-HAADF image of lignin carbon nanofibre 20A35F4-250-5-60-1000-10-60 with the in-situ synthesized nanoparticles and mapping of carbon, iron, oxygen and sulfur .................................................................................................................................... 165 Figure A-12 XRD pattern of CNF obtained from electrospun fibres with different amount of 1% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 166 Figure A-13 XRD pattern of CNF obtained from electrospun fibres with different amount of 3% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 167 Figure A-14 XRD pattern of CNF obtained from electrospun fibres with different amount of 5% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 168 Figure A-15 XRD pattern of CNF obtained from electrospun fibres with different amount of 10% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 169       xix  Figure A-16 XRD pattern of CNF obtained from electrospun fibres with different amount of 20% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 170 Figure A-17 XRD pattern of CNF obtained from electrospun fibres with different amount of 1% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 171 Figure A-18 XRD pattern of CNF obtained from electrospun fibres with different amount of 3% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 172 Figure A-19 XRD pattern of CNF obtained from electrospun fibres with different amount of 5% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 173 Figure A-20 XRD pattern of CNF obtained from electrospun fibres with different amount of 10% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 174 Figure A-21 XRD pattern of CNF obtained from electrospun fibres with different amount of 20% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 175 Figure A-22 XRD pattern of CNF obtained from electrospun fibres with different amount of 3% IAA with 3˚C/min at 250˚C for 60min and carbonized at 1000˚C ............................................. 176 Figure A-23 DSC of F1-3 powder ................................................................................................ 177 Figure A-24 mDSC of F4 ............................................................................................................ 177 Figure A-25 DSC of acetylated-F4 .............................................................................................. 178          xx  List of Abbreviations CE: counter electrode CF: carbon fibre CNF: carbon nanofibre D band: disordered carbon band DMF: dimethylformamide  DSC: differential scanning calorimetry EDX: energy-dispersive X-ray  emu: electromagnetic unit F1-3: methanol soluble lignin fraction from SKL  F4: methylene chloride soluble lignin fraction from F3SKL-free SKL  FT-IR: Fourier transform infrared spectroscopy  G band: graphitic carbon band HAADF: high-angle annular dark-field HRTEM: high resolution transmission electron microscope IAA: iron acetylacetonate MALLS: multi-angle laser light scattering  NMR: nuclear magnetic resonance  PAN: polyacrylonitrile  PEO: poly(ethylene oxide)  RE: reference electrode SAED: selected area electron diffractions       xxi  SEM: scanning electron microscope SKL: softwood Kraft lignin  STEM: scanning transmission electron microscope SQUID: superconducting quantum interference device  TEM: transmission electron microscopy  TGA: thermogravimetric analysis  THF: tetrahydrofuran  XRD: X-ray diffraction XPS: X-ray Photoelectron Spectroscopy WE: working electrode          xxii  Acknowledgements First and foremost, I’d like to thank my supervisor Professor Frank Ko, who welcomed me into the Advanced Fibrous Materials Laboratory as his PhD student. I am forever grateful for his support and guidance through these years. His example has strongly shaped my approach to research and will continue to do so throughout my career.  I’d like to acknowledge Prof. Rizhi Wang, Prof. Peyman Servati, Prof. John Madden and Prof. Scott Renneckar for their insightful suggestions for my research.  I’d like to thank Prof. John Kadla, Dr. Ian Dallmeyer and Ms. Nai-Yu Teng help me for lignin fractionation and molecular weight characterization. Thank Prof. Dave Michelson and Mr. Andrew Mei for training me for EMI shielding test. Thank Mr. Eddie Fok, Dr. Ashwin Usgaocar, and Dr. Ali Mahmoudzadeh for training me for the battery assembly and test. Thank Dr. Saeid Soltanian for training me for the flexible bending test. Thank Prof. Kati Zhong and Mr. Yu Wang  for helping me with the flexible battery assembly and measurement at Washington State University. Thank Yan Tan, Chad Atkins, Prof Maggie Xia, Ms. Ye Zhu for training me for Raman Spectroscopy. Thank Dr. Pinder Dosanjh for training me for SQUID. Thank Dr. Xin Zhang for training me using STEM. Thank Dr. Bo Deng for helping me with the contact angle measurement. Thank Ken Wong for XPS measurement. Thank Hamid Azizi providing me the access into XRD during the holidays. I also wish to express my thanks to everyone from UBC AFML lab and UBC Advanced Biomaterials Chemistry lab, Dr. Heejea Yang, Dr. Lynn Wan, Dr. Addie Bahi, Dr. Guangzheng (George) Gao, Dr. Muzaffer Karaaslan, Dr. Yue Ma, Dr. Mirjam Mai, Dr. Reza Korehei, Dr. Ana Fillipa Xavier, Mr. Litng Lin, Ms. Mijung Cho, Ms. Masoumeh Bayat, Mr.      xxiii  Justin Richie, Dr. Jinfeng Wang and Dr. Yantao Gao. Thank Ms. Michelle Tierney, Dr. Ryan Whitehead and Mr. Roli Wilhelm to proof read my thesis.  I’d like to acknowledge generous financial support from NSERC Lignoworks and NSERC FIBRE (Forest Innovation by Research & Education) Network for my research. I’d also to thank my sweet friends in Canada and in China, Yuan Ruan, Jianglan Duan, Yu Du, Rao Pan, Yang Yang, and Donghui Wu, for providing me mental supports and enabling me to go through the grinds of my Ph.D. journey. Last but not least, I appreciate my parents and my sister who always love me unconditionally, support me and believe in me over the years.        xxiv  Dedication To my parents and my sister        1  Chapter 1 : Introduction In order to decrease human dependence on petroleum, it is essential to develop ecologically friendly materials from the sustainable and renewable resources. Energy demand is increasing with the both the ongoing growth in world population and the industrialization of nations. This increase in demand is causing crisis plethora of energy crises, profound climate change and local environmental issues. Reducing oil consumption is a key goal to ensure sustainable development of our world society. One of the top uses of crude oil is the production of materials. Therefore, there is a growing urgency to develop materials derived from sustainable and renewable resource to reduce oil use.  An important renewable resource is wood provided by means of forestry. Canada is rich in forest resources, and is the largest exporter of paper in the world. The Forest Industry is one the cornerstones of Canada’s economy at $80 billion per year, representing 3% of the net Gross National Produc (GNP).1 It operates in over 320 communities across the country and provides 900,000 jobs direct and indirectly.1 A number of factors, both domestic and international, have led to reduced production, a decline in profitability, mill closures and job losses in Canada’s forest products industry.2 The forest industry is at a crossroads and must adapt in order to thrive. The production of novel, high value products as a complement to its traditional commodity products is a path to a sustainable future.  This research was funded by Canada NSERC Biomaterials and Chemicals Strategic Research Network (Lignoworks). The aim of Lignoworks is to provide a pathway to develop value-added products from renewable forest-based lignin. This endeavour is expected to yield       2  alternatives to fossil fuel feedstock by creating technology platforms for lignin-based materials. At the same time, it will also provide considerable benefit to traditional pulp mills by diversifying the range of products they can offer.  Lignin is nature’s dominant aromatic polymer, found in most terrestrial plants in the approximate dry weight range of 15 to 40%.3 Lignin provides structural integrity, binding the cells, fibres and vessels which constitute wood and the lignified elements of plants (such as straw). Next to cellulose, it is the most abundant renewable natural polymer on earth. In industry, lignin is a co-product of the pulping and paper making process. Between 40 and 50 million tons per annum are produced worldwide, mostly as a non-commercialized waste product.4  Recovered lignins are typically treated as waste and burned to produce heat for factories at very low efficiency. Only 2% of technical lignins are currently converted to commercial products, which currently include dispersants, emulsion stabilizers, surfactants, and binders.  Recent research has been conducted on the utilization of lignin for value-added products. Potential high-value products from isolated lignin include low cost carbon fibre 5–9, engineering plastics10,11, thermoplastic elastomers12, polymeric foams13, and a variety of fuels and chemicals3, all currently sourced from petroleum. However, it is still challenging for these product streams to be low cost and to perform as well as their petroleum-derived counterparts.  The challenges come from the highly complex, heterogeneous chemical structure of lignin which makes isolation, characterization and processing very difficult. Nonetheless lignin has numerous unexplored functional groups, including methoxyl groups, hydroxyl groups, and       3  large amount of aromatic rings, which may have huge untapped potential in terms of harnessing chemical function.  This thesis will work towards narrowing the knowledge gap with regard to harnessing complex lignin chemical structures to enable functionalization of lignin fibres for advanced functional applications. One way to add novel functional properties to lignin is to process lignin into nanofibres by electrospinning. Electrospinning is a remarkably simple and powerful technique for generating ultrathin fibres capable of yielding highly unique and attractive features. Electrospun nanofibres are commonly submicron fibres, typically in the range of 100–1000 nm. By reducing the fibre diameter to the nanometer level, nanofibres possess high surface areas and often improved mechanical properties.14 With higher surface area, the functional groups of lignin will be more effectively utilized. A smaller fibre diameter will also lead to the possibility of improving the tensile strength of nanofibres due to a decrease in structural defects and increase in molecular orientation14. The resultng nanofibres are typically assembled as a non-woven web of entangled fibres, but other assembly architectures ( such as continuous single nanofibre filaments, aligned nanofibre sheets, nanofibre non-woven mat, nanofibre yarns, and interconnected fibres) can also be obtained by controlling the collection of nanofibres during electrospinning. Therefore, converting raw materials into nanofibre form or fibres with diameters on the submicron level will add functionality to raw materials and lead to value-added products.  By thermostabilizing electrospun lignin nanofibres in air atmosphere, chemical functionality can be added to lignin to produce value-added products. Chemical reactions occur during thermostablization, analogous to thermostabilization of pitch-based carbon fibres,       4  including oxidation, dehydrogenation, elimination, condensation, and cross-linking.15 For complex structure such as lignin, cross-links between lignin, molecules are formed during a series of reactions such as free radical oxidation, molecular rearrangement, dehydrogenation, and condensations. One known reaction is the formation of carbonyl groups through homolysis of the β-O-4 ether bonds in lignin16. With the formation of such functional groups by thermostablization, chemical functions can be added to lignin. By carbonizing thermostabilized electrospun lignin nanofibres in nitrogen environment at high temperature, carbon nanofibres (CNFs) are able to be obtained. A higher degree of electrical conductivity can also be added to lignin to produce value-added products. CNFs are approximately two to three orders of magnitude thinner than their conventional carbon fibres. With the reduction of fibre diameter, there is a strong possibility of improving the tensile strength of carbon fibres. Therefore, converting lignin into CNFs will further expand its functionality and lead to more value-added products. Indeed, lignin-based CNFs are thought to have great potential to for use in applications such as energy storage17,18 and electrometric interference shielding19,20.  Besides electrospinning, thermostabilizing and carbonizing lignin nanofibres, electrospun fibres and CNFs could also serve as material platforms from which novel functionalized materials could be developed. Functions could be introduced to electrospun lignin nanofibres by (1) designing composite nanofibre; or (2) preparing architecturally-designed nanofibres. Composite nanofibre can be prepared by embedding functional nanoparticles within nanofibres to introduce specific functions (electrical functions, magnetic functions, electrochemical       5  functions etc.) to the fibre matrix. The architecture of ultrafine lignin fibre can also be designed to functionalize lignin nanofibres. Fibre structures (such as porous, core-shell, or hollow structures) and fibre assembly architectures (random, aligned, or inter-connected carbon nanofibre etc.) can therefore be designed and prepared. These various structures thus lead to interesting properties and functions and applications. Currently, the main challenges for utilizing lignin for multifunctional nanofibres still come from the highly complex, heterogeneous chemical structure of lignin. Currently, the resultant performance of the multifunctional nanofibres is not yet as competitive as that of the petroleum-based nanofibres. Therefore, the fundamental understanding of its basic chemistry, and the properties of advanced applications of lignin-based multifunctional nanofibres must be further explored on a basic science level.  We will therefore explore the multifunctional pathways of lignin nanofibres to add function to lignin products at many different levels. We will illustrate the multifunctional capabilities generated by lignin through products including EMI shielding, batteries and actuators.            6  Chapter 2 : Literature Review 2.1 Lignin  In nature, lignins are one of three main constituents of plant cell walls. Lignins serve as structural elements imparting rigidity and resistance to impact, compression, and bending. In addition, they facilitate the transport of water, nutrients and metabolites and provide resistance against degradation by microorganisms 21. Generally, lignin is considered to be a random three-dimensional polymer network comprised of phenyl-propane units linked together by a variety of bond-types  (Figure 2-1) 22. The three major monomers which are bonded through free-radical oxidation are p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. The chemical structure of lignin monomers and linkages which constitute these networks differ depending on morphological regions of the cell walls (middle lamella vs. secondary wall), different types of cells (vessels vs. fibres) and different types of wood (softwood vs. hardwood)  21,23.                        Figure 2-1 Three monolignol monomer structures and an example of a possible corresponding lignin structure 22(1:p-coumaryl alcohol, 2: coniferyl alcohol and 3:sinapyl alcohol)        7  Commercially, lignin is a byproduct of wood-free papermaking process 16. Vast amounts of lignin are separated from wood and then burned internally to produce steam and electricity. Different methods of isolation generate different types of technical lignin. The main source for technical lignins is the black liquor from the kraft pulping process. Kraft lignin is the most abundant and inexpensive lignin due to the standard use of kraft processing in the pulp and paper industry. When wood is treated with a Na2S/NaOH solution at a temperature range of 155–175 °C for several hours, solid (cellulose) and fluid (black liquid) fractions can be separated. Kraft lignin is obtained by a delignification process, in which the black liquid is precipitated, neutralized with an acid solution (pH 1–2) and dried to a solid form 24,25. The treatment yields a lignin that is highly modified and soluble only in a strong aqueous base 24. Besides, ligninsulfonates, organosolv lignin and steam exploded lignin derived from other extractions and isolation procedures are commercially available as well 24. Recovered lignins are typically treated as waste and burned to produce heat for the factory. About 2% of technical lignins are currently converted to products including dispersants, emulsion stabilizers, surfactants, and binders. Technical lignins are also being tested as thermoplastics and in thermosetting resin systems 10,11. The relatively limited utilization of industrial lignins is due to the highly complex, heterogeneous chemical structure of lignin which makes isolation, characterization and processing very challenging.    2.2 Carbon Fibre  To add value to lignin, it can be converted to various product forms, including carbon fibre (CF), surfactant, resin, additives and solid fuel. Among the lignin based commercial products, carbon fibre has been identified as one of the most promising high value added options       8  for lignin. According to the market report, the global carbon fibre market size is forecast to have an annual growth rate of 17% from 2012 to 2017, reaching 118,600 tonnes, with an estimated market value of $7.3 billion by 2017 26. Due to its unique mechanical properties carbon fibre can be used in aerospace, automotive and sports applications. And because of its unique electrical properties, carbon fibres can be used as electrodes, supercapacitors and so on. The carbon fibre industry is also looking for low cost renewable carbon precursor. In summary, conversion of lignin into carbon nanofibres will add high values to lignin and will benefit carbon fibre industry.  In the 1960s, carbon fibres were to become breakthrough industrial materials for modern science and technology. Demand for carbon fibres, as lightweight materials, has been found in numerous industries such as aerospace, automotive, sport equipment and other consumer products. Carbon fibres are also burgeoning industry in electrical and electronics industry and the energy storage area. Typical applications include brush contact in commutator brush, position sensor, switches and static discharge eliminator devices 15, electrodes  in capacitors and batteries 27–29, and electromagnetic interference shields 15,30.  Conventionally, carbon fibre is a material consisting of fibres about 5-10 micron in diameter and composed mostly of carbon atoms (at least 90%). Carbon fibres are produced from various carbon precursors, such as polyacrylonitrile (PAN), rayon and pitch 31. Producing carbon fibres is a multi-stages process, including the dope formulation, spinning, heat treatment and specific post treatments. The production processes and properties for the petroleum based carbon fibres will be described in detail below.         9  2.2.1 Spinning  Polyacrylonitrile (PAN) is a synthetic, semi-crystalline polymer with the linear formula (C3H3N)n; the chemical structure is shown in Figure 2-2.  Unlike lignin, it does not contain any aromatic carbon structures and is a more linear polymer. Precursor for commercial carbon fibre manufacture is not PAN homopolymer, but PAN co-polymer together with, for example, acrylic or itaconic acids.15  PAN co-polymer must have acrylonitrile content greater than 85%, preferably 90–95% and the choice of co-monomers can influence the relative ease of processing. Wet spinning is used for most commercial PAN based carbon fibre precursor process and is gradually being replaced by air gap (dry jet wet) spinning 15. The processing sequence for PAN is shown in Figure 2-4 (a). Highly oriented polymer chains are obtained in PAN by hot stretching 26.   Figure 2-2 Chemical structure of PAN   Pitch is the by-product of the petroleum and coal-chemical industries (such as petroleum refined residue, coal tar pitch, and the residue of solvent refined coal and petroleum). Pitch is a polyaromatic carbon, which makes it more similar to the aromatic carbon containing lignin, but different in that lignin is mainly linked by arylglycerol-β-aryl ether bonds and is not polyaromatic. The chemical structure of pitch is shown in Figure 2-3. Depending on the specific       10  pretreatment of the raw pitch material, there are two categories of precursor material for making carbon fibres: isotropic pitch and anisotropic pitch. Generally, isotropic pitch serves as the precursor for manufacturing general performance carbon fibre, whereas anisotropic pitch is the feedstock in making high performance carbon fibre  15.    Figure 2-3 Chemical structure of pitch 15  Generally, pitch is composed of four main classes of chemical compounds: 1. Saturates-low molecular weight aliphatic compounds, 2. Naphthene aromatics-low molecular weight aromatics and saturated ring structures, 3. Polar aromatics-higher molecular weight and more heterocyclic in nature; 4. Asphaltenes-which is the highest molecular weight fraction in pitch with the highest aromaticity and thermal stability 15. Due to the complexity of the chemical composition of raw pitch, it is necessary to refine pitch to get rid of impurities such as solids and primary quinolin-insoluble matter. After refinement, the purified pitch typically has low ash, low       11  heteroatom, low metal ion content and high aromaticity. Industrial pretreatments, or refinement methods, are generally proprietary processes which usually involve multiple steps, including solvent refinement 32, distillation and super critical fluid extraction 15.   Take mesophase pitch as an example, the pitch is cleaned to remove volatile compounds in vacuum, after that, the pitch is heated to 350–500 °C in an inert atmosphere. During this temperature treatment, a mesophase is built via the condensation of pitch oligomers. However, the resulting mesophase has the advantage that a melt-spinning process can be applied instead of a solution-based process for fibre spinning. In course of this melt spinning process, the precursor fibre experiences a very high orientation of the aromatic layers, which is then directly transformed into the final carbon fibre 27. The processing sequence mesophase-pitch-based precursor fibers is shown in Figure 2-4 (b). High orientation in pitch is a natural consequence of the mesophase (liquid crystalline) order 26.        Figure 2-4 The processing sequence for PAN (a) and mesophase-pitch-based precursor fibers (b) shows similarities for the two processes. Highly oriented polymer molecular chains are obtained in PAN by hot stretching, while high orientation in pitch is a natural consequence of the mesophase (liquid crystalline) order 31 a b       12   2.2.2 Heat Treatment Heat treatment is an intermediate process that converts the as-spun polymeric fibre to carbon fibre. The successful conversion of as-spun polymeric fibre to carbon fibres depends upon the understanding of the heat treatment processes. Three steps are listed for the conversion of precursor of polymeric fibre to carbon fibre, thermostabilization, carbonization and graphitization33–35.  The first step is thermostabilization, usually in the temperature range of 200 ~ 400˚C and in an oxidative gas environment, typically air. Thermostabilization involves complex chemical reactions, including dehydration, oxidation, crosslinking, and cyclization. Reactions occurring during thermostabilization increase the glass transition temperature Tg. At a fast heating rate, Tg falls behind the processing temperature, fibres fuse together 16. At a slow heating rate, Tg is maintained above the processing temperature, fibres retain its original morphology 16. Therefore, ramping rate is a crucial parameter in the thermostabilization stage. The second step is carbonization (≤1600 °C) to eliminate non-carbon atoms and yield a turbostratic structure. The third step is graphitization by heating up to 2000 °C to improve the orientation of the basal planes and thus the stiffness of fibres.  2.2.3 Mechanical Properties The diameter of commercial PAN based carbon fibre is about 7 micron. The tensile strength is 3 ~ 7 GPa, and modulus is 220 ~ 600 GPa, depending on the degree of graphitization 15. The diameter of pitch based carbon fibre is about 11 micron. The tensile strength is 1.3 ~ 2.4 GPa and modulus is about 170 ~ 970 GPa 3115.          13   2.3 Carbon Fibre from Lignin At the present time, about 95% of carbon fibre precursors are polyacrynitrile (PAN) 7. The precursor cost of PAN based carbon fibre was over 50% of the total manufacturing cost of the carbon fibre 7. In 2010, the commercial grade PAN based carbon fibre manufacturing cost was around $9.88/lb 5. Carbon fibre industry is looking for low cost renewable precursor. If the carbon fibre precursor is replaced by lignin, the carbon fibre cost could be reduced to $3.71/lb  5.  Lignin is an excellent candidate as a low cost renewable carbon fibre precursor.  Lignin based carbon fibre have successfully been prepared by dry-spinning or melt-spinning. Lignin was modified to be dry-spun or melt spun into fibres. Lignin fibres were dry spun from alkali lignin, thiolignin and ligninsulfonate dissolved in an alkali solution with poly (vinyl alcohol) added as a plasticizer 36. Lignin was melt spun from steam-exploded lignin modified by hydrocracking, phenolation, or hydrogenolysis methods  37,38. Lignin fibres were melt spun from hardwood lignin and synthetic polymer blend fibres poly (ethylene terephthalate) (PET) and polypropylene (PP) 8,9.   Lignins were acetylated and, when melt, extruded into continuous fibres 39. The Oak Ridge National Laboratory (ORNL) melt spun a kraft hardwood lignin (HWL) and an organic-purified hardwood lignin (HWL-OP) into fibres7.  Lignin carbon fibre has tensile strength about 0.5~0.7 GPa and tensile modulus of 28~90 GPa 8,9.  The mechanical properties of lignin-based carbon fibres have yet to meet the industry requirements for high performance fibres. There are still many difficulties for the recovered lignin from paper mills to satisfy the purity levels and physical properties sufficient for carbon       14  fibre manufacturing. It is still a challenge to prepare lignin-based carbon fibre with the high mechanical strength and low manufacturing cost that industry demands.  In summary, the relatively poor mechanical properties of lignin-based CFs are barriers to their structural application use in the near future. In order to address the issue of mechanical properties, it is proposed to produce nanofibres from lignin by electrospinning. By reducing the diameter of the fibre down to the nanoscale by electrospinning, the probability of the structural defects will be reduced thus to improve the mechanical properties. Furthermore, converting lignin into nanofibres form will further expand its functionality and lead to more value-added products. 2.4 Electrospinning of Lignin  Electrospinning was conducted to convert lignin into nanofibre. With the rediscovery of electrospinning in the late 1990s, manufacturing nanofibres from various polymers using electrospinning technique attracted much interest 40–44 , due to its simplicity, versatility, and availability. Electrospinning is a process to draw a continuous fibre from a polymer solution, using electrostatic forces. In electrospinning, a droplet of polymer solution will be pending at the tip of the nozzle, which then forms a conical shape ( known as  the Taylor cone) by the applied electric field.14  When the electrostatic forces are high enough to overcome the surface tension of the polymer solution, the solution is ejected towards the ground collector in a spiral whipping motion and evaporating of the resulting in highly elongated filaments having nanoscale diameters.14  Conversion of lignin into electrospun nanofibres has been conducted.  Organosolv lignin (Alcell) were reported to be the first type of lignin to be electrospun into nanofibres 45.        15  Organosolv lignin (Alcell) was dissolved into ethanol and electrospun into ultrafibres (400nm to 2μm) using coaxial spinneret.  Moreover, other types of technical lignins were investigate to be electrospun into nanofibres using single nozzle method46. In this study, seven different technical unfractionated lignins (softwood kraft lignin, hardwood kraft lignin, and sulfonated kraft lignin, hardwood organosolv lignin, alcell lignin , softwood organosolv lignin, pyrolytic lignin  and lignosulfonate) were electrospun into fibres through the addition of appropriate amount of polyethylene oxide (PEO) (1 ~ 5 wt% of mass of the lignin). Without blending PEO, substantial beads or discreet fibres were formed during the electrospinning process.  The main obstacles for the continuously electrospinning of lignin into uniform nanofibres are the complex, heterogeneous chemical structure, the broad distribution of molecular weight and the variability in properties among different types of isolated lignins. In order to prepare lignin more readily for electrospinning, lignin was divided into different fractions to improve the spinablility. For example, commercially available Softwood Kraft lignin (SKL) with high molecular weight distribution was divided into fractions by successive extraction with organic solvents 47,48 or by membrane ultrafiltration 49,50 for further electrospinning. Parameters for continuous electrospinning nanofibre from different lignin fractions have been established 51. It was reported the 4th fractionation SKL has proper molecular weight and molecular weight distribution for electrospinning.51,52 Lignin-based electrospun nanofibres have been converted into carbon nanofibres by thermostabilization and carbonization in recent studies 52–54. To date, the reported tensile strength of the lignin carbon nanofibre mat was 50~66 MPa after carbonization at 1000˚C.55  Lignin-based carbon nanofibres have not reached similar mechanical properties as PAN-based       16  commercial carbon fibres for structural composite applications. The complex branching molecular structure of lignin remains to be the main reasons for the poor mechanical properties.  Besides mechanical properties, functional properties of lignin-based electrospun fibres and carbonized fibres need to be studied for non-structural applications. In this thesis, we hypothesised functionalization of lignin-based nanofibres and lignin-based carbon nanofibres are achievable. But we have to overcome and take advantage of complexity of lignin chemical structures, enabling functionalization of lignin fibres for advanced functional applications. 2.5 Multifunctional Nanofibre  Moreover, electrospun fibres could serve as materials platforms from which novel functionalized materials can be developed. Herein, we generally summarize the potential methods for adding functionalities to lignin nanofibres. Specially, functions could be introduced to electrospun lignin nanofibres at the levels: i) molecular level, ii) fibre level, and iii) assembly level. 2.5.1 Functions Added at the Molecular Level Functionality can be introduced at the molecular level to electrospun fibres from lignin, as lignins possess large amount of different functional groups available for functionalization and modification. For example, surface modification through immobilization of polymer brushes is a very effective way to design new materials with novel functionalities 40,56,57. The surface of lignin electrospun fibres modified with pANIPAM offers temperature and ionic response surface properties 58,59.  Gao et al. reported surface modification of electrospun lignin nanofibres with poly(N-isopropylacrylamide) (pNIPAM) through surface-initiated atom transfer radical       17  polymerization5958. pNIPAM is an amphiphilic  stimuli-responsive polymer with a lower critical solution temperature (LCST) around 32˚C 59. In Gao’s work, analysis of the PNIPAM-grafted lignin nanofibre mats found that the LCST was similar to that of PNIPAM, and demonstrated environmentally sensitive characteristics, such as an ion concentration dependent LCST and an ionic responsive surface (expanding in water and contracting in a 0.5M Na2SO4 aqueous solution)59 . Such surface modification of lignin fibre mats may enable lignin utilization in a wide range of applications, such as permeation as permeation-controlled filters60,61, chemical sensors62,63, attachment/detachment controllable surfaces for proteins64,65, and living cells66,67, medical diagnostic devices,68,69 functional composite surfaces70, as well as thermo-reversible separators, thermo-responsive soft actuators, automatic gel valves, and smart, reusable catalysts 71–75. 2.5.2 Functions Added at the Fibre Level Multifunctional composite nanofibres could be prepared by co-electrospinning of nanoparticles with the polymer with subsequent thermostabilization and carbonization. Nanoparticles of various geometries and properties can be combined with a suitable polymer matrix by co-electrospinning to form composite nanofibres. Among the various available nanomaterials with 0-D, 1-D, and 2-D geometry, magnetic nanoparticles, quantum dots, photocatalytic nanoparticles and carbon nanotubes are excellent examples, which have been incorporated into the electrospinning process to fabricate composites fibres with interesting functions. For example, iron oxide nanoparticles can be used for biomedical applications, electromagnetic interference shielding, catalysts and sensors 76. Quantum dots such as CdS, CdSe and ZnS can be used in semiconductive devices, biological labelling and optical switches       18  77–81. TiO2 particle have been known for its strong photocatalytic properties, and can be used for filtration and antibacterial applications 82,83. Carbon nanotubes has brought great attentions due to its superb mechanical and electrical properties 84. The preparation of multifunctional composite nanofibres with functional nanoparticles through electrospinning process is a very promising general method to transfer functions from nanoparticles to polymer to enhance the overall performance value of such polymer materials. Subsequently, the electrospun composite nanofibres are carbonized to carbon nanofibre to obtain composite carbon nanofibre for advanced applications such as the EMI shielding and energy storage applications 85–89. As mentioned before, although lignin-based CFs have been studied for decades, limited research can be found on lignin-based composite carbon nanofibres. Teng et.al reported on using lignin to disperse multiwall carbon nanotubes, which were subsequently used to reinforce lignin-based carbon nanofibres 90,91. Alcell lignin was electrospun into hollow fibres through a coaxial spinneret system45. Submicron diameter fibres were produced by the electrospinning of alcell lignin/ethanol/platinum acetyl acetonate and lignin/ethanol solutions, respectively 6. Lignin carbon nanofibres with and without platinum were prepared, however, the fundamental properties characterization and advanced applications have yet to be conducted at this time.  Multifunctional composite nanofibres could be prepared by co-electrospinning of blended polymers. For example, blends of kraft lignin fractions from softwood with different physical properties were electrospun into fibres and moisture-responsive Kraft lignin-based materials were prepared51. The differences in thermal mobility between lignin fractions were shown to influence the degree of inter-fibre fusion occurring during oxidative thermostabilization of the       19  electrospun nonwoven fabrics which resulted in different material morphologies. These included submicron meter fibres, bonded nonwovens, porous films, and smooth films 51.  Furthermore, at the fibre level, fibre structures and geometry (porous 92–96, core-shell 97,98 or hollow structures 45,99–102) can be designed to add functionality. For example, porous ultra-fine fibres were prepared via selective thermal degradation of electrospun polyetherimide/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PEI/PHBV) fibres103. Porous ultrafine PGA fibres were obtained via selective dissolution of electrospun PGA / PLA blend fibres 104. Using the porous carbon nanofibres as an example, it has ignited the significant attention due to the enhancement of surface area, pore size distribution and ionic accessibility into the porous material. Extensive studies has been conducted using porous carbon nanofibres for the electrodes of supercapacitors and batteries88,105–108.  2.5.3 Functions Added at the Assembly Level  Fibre assembly architectures (random, aligned, or inter-connected carbon nanofibre) can be designed and prepared. Multiphase polymeric systems, such as blended polymers are also able to be co-electrospun and carbonized into carbon nanofibres with different architecture.  Kraft lignin-based carbon nanofibres with inter-connected architecture were prepared by electrospinning blends of kraft lignin fractions from softwood with different physical properties51. It should be noted that inter-connected architecture was able to improve the electrical conductivity of carbon nanofibres through the connected network pathway52.   The interconnected electrospun carbon nanofibres have the potential to be used for batteries electrodes109,110       20  Carbon nanofibres typically have a nonwoven-like fibrous structure. For electrochemistry-associated processes, nonwoven structures may have low charge-transfer efficiency because of the insufficient fibre–fibre contact leading to large contact-resistance and prolonged charge-transfer. The lack of inter-fibre connection may also reduce the pore stability 28,111 It was found that inter-connected carbon fibres have better electrochemical capacitance 112 113. It has been demonstrated that inter-connected architecture can help to improve the electrical conductivity of carbon nanofibres through the integration of an connected network pathway52.   2.6 Applications of Multifunctional Nanofibre Energy and environment problems are the problems that humanity will face over the next 50 Years. With the rapid growth of information technology it is also expected expanded demand for electronic devices. Therefore, it is anticipated tremendous opportunity in products related to energy, environment and electronics for lignin-based carbon nanofibres. Herein, we summarize some potential applications of multifunctional nanofibres in the areas related to electronic devices, energy storage and environments. 2.6.1 EMI Shielding Application By utilizing the high electrical conductivity of carbon nanofibre, one suitable application is EMI shielding. PAN-based CNFs have been investigated as EMI shield 20. It is necessary to study if lignin-based EMI shield will be low cost and perform as well as the petroleum-derived counterparts. Electromagnetic compatibility has become a significant challenge for product design with the miniaturization and increasing operating frequencies of electronic devices. The protection of electronic circuits from electrostatic discharge and radiated electromagnetic interference (EMI) is       21  of growing importance. Currently, commercially available materials for EMI shielding are mainly metal coated or metal plated polymers. In 2006, the demand for EMI/RFI shielding options was about $725 M. 114 The global market for electromagnetic interference/radio frequency interference materials and technologies is expected to increase to nearly $5.2 billion in 2016, for a compound annual growth rate (CAGR) of 2.8% 115. The largest segment of the market, made up of conductive coatings, is expected to increase at a 5-year CAGR of 1.9%, rising from an estimated $1.7 billion in 2011 to nearly $1.9 billion in 2016 115.  For any kind of electromagnetic interference, there are three mechanisms contributing to the effectiveness of a shield. As seen in Figure 2-5, EMI shielding is the consequence of reflection loss, absorption loss, and internal reflection loss at exiting interfaces of the incident electromagnetic waves in the sample. Therefore, the total shielding effectiveness of a shielding material (SE) is the sum of the absorption factor (SEA), the reflection factor (SER), and the correction factor to account for multiple reflections in thin shields (SEB): SE=SEA+SER+SEB.116 Multiple reflections SEB are neglected when SEA>10dB. 1/220 ( ) ( )2r acASE d Log e   equation 1 010 ( )16acRrSE dLog    equation 2 where σac: electrical conductivity; μr magnetic  permeability; ω: frequency; d: sample thickness. According  to  equations  (1)  and  (2),  SEA  varies proportionally with the product of electrical conductivity  and  magnetic  permeability  (σacμr), while SER is proportional to the σac/μr. The first mechanism is reflection which requires that the shielding material be electrical       22  conductive. Composites containing 117 conductive fillers  such  as  carbon  nanofibres  118,119 and carbon  nanotubes 120  are  known to reflect  electromagnetic wave. The second mechanism of EMI shielding is absorption, and requires electric and/or magnetic dipoles which interact with the electromagnetic fields. 86,121–123 Carbon nanofibre based materials can potentially meet these requirements of “thin, lightweight, strong, broad frequency” on EMI shielding materials. Carbon nanofibres with high aspect ratios have a high electrical conductivity and high specific surface area and fibres with diameters less than 4.1 µm could be used as light weight EM wave absorbers without performance degradation 119. The reason being that skin depth for carbon fibres is from 12.6 to 4.1 µm under 2 to 18 GHz 124. Furthermore, recent studies have already shown that composite carbon nanofibres (petroleum-based carbon nanofibres) are excellent candidates for electromagnetic interference (EMI) shielding 20,86,121,125,126. In this thesis, we explored the feasibility of lignin-based CNF for EMI shielding applications and compared its performance with that of the petroleum-based CNF shields.        23   Figure 2-5 EMI Shielding mechanisms 116   2.6.2 Application to LIB Batteries Electrodes By utilizing the electrical conductivity of carbon nanofibre, second suitable application is lithium ion batteries (LIB). LIBs are one of the most important technologies of the early 21st century and are pervasive in modern infrastructure. To date, lithium ion batteries have primarily been used for consumer applications such as mobile phones, portable PCs, power tools and other equipment requiring rechargeable power. However, the market for lithium ion batteries is growing to include hybrid electric car (HEV) batteries and energy storage systems (ESS). The predicted market expansion of LIBs from 2010 to 2020 is surprising with a ten-fold growth from 11.6 to 119.3 billion US dollar (USD) 127.  LIB technology faces many challenges in terms of safety, cost, optimized energy density and power density. Many of these challenges are associated with the use of a highly reactive liquid electrolyte. To understand the challenges faced by liquid-based LIB technology, it is       24  necessary to understand the structure of a battery. As seen in Table 2-1, a battery typically consists of three main components: the anode (negative electrode), the electrolyte and the cathode (positive electrode). During discharge, lithium ions migrate through the liquid electrolyte from the anode to the cathode, a polymer separator electrically isolates the cathode from the anode 128. The liquid electrolyte is typically LiPF6 dissolved in a mixture of organic solvents (e.g. dimethyl carbonate, diethyl carbonate, ethylene carbonate). The performance of the battery is in part determined by the performance of the electrolyte.  It is, therefore, desirable for the electrolyte to have a very high ionic conductivity to facilitate rapid shuttling of lithium ions between the electrodes to maximize power delivery, while having very low electrical conductivity to limit self-discharge and prolong shelf-life 129. There are serious safety concerns regarding the use of liquid electrolytes. The use of organic-based solvents makes the electrolyte solution highly volatile under extreme operating conditions (high temperatures, high charge–discharge rates, puncturing, etc) leading to safety concerns about battery flammability and personal safety 130. To address these challenges, solid-state batteries with solid electrolytes have been developed over the past 20 years. Although still in its infancy, recent developments and continued interest indicate a promising future for solid-state batteries for many energy storage applications 131.  Solid electrolyte can be inorganic materials (oxide, sulfide etc.) or polymer-based materials. Solid polymer electrolyte (SPE) attracts great attentions due to its light-weight, leak proof, shape versatility and flexibility. A typical solid state battery configuration can be viewed in Table 2-1. In summary, the above comparisons between conventional Li-ion rechargeable battery and solid state battery have illustrated in Table 2-1.        25  Developments of highly conductive solid electrolytes are currently in progress, however, no matter how high the ionic conductivity becomes, the power density of the battery won’t be improved without reducing the interfacial resistance 132. As the name implies, in all- solid-state systems, all components exist as solids. This alters the chemistry associated with lithium ion transport and electrolyte interfaces. Understanding these mechanisms of interaction associated with electrode and solid electrolytes is essential in developing more reliable and high performance solid-state LIBs. Table 2-1 Comparison between conventional Li-ion rechargeable battery and solid state battery133  Type Conventional Li-ion rechargeable battery Solid state battery Structure   Electrolyte Organic liquid electrolyte (PC etc. as solvent, LiPF6 etc. as salt) polymer immersed in liquid organic electrolyte (Li-polymer rechargeable battery Inorganic materials (sulfide, oxide, etc.) Polymer material (PEO etc.)  The power of LIB is influenced by the rate of the lithium ion diffusion in and out of the electrode structures. Nanostructured electrodes such as nanofibres having at least one dimension with nanometer size have been considered. It is expected that implementation of nanostructures may result in the reduction of the diffusion length of the lithium ions in and out of the electrodes       26  and thus in the enhancement of the electrode charge-discharge rated. On the other hand, because of the large surface to volume ratio, the use of nanostructures is expected to result in an increase of the electrochemical active surface by many orders of magnitude to address the big interface resistance problem between solid state electrodes and solid electrolyte. PAN-based CNF LIB electrodes have been manufactured and tested and are exhibiting favorable characteristics such as: a large accessible surface area (derived from the nanometer-sized fibre diameter), high carbon purity (without binder), relatively high electrical conductivity, structural integrity, thin web morphology, a large reversible capacity (ca. 450 mA h /g), and a relatively linearly inclined voltage profile 93,134,135.  It has been confirmed that carbon nanofibres have advantages of rate capabilities. For example, considering the rate capability (30, 50, and 100 mA/g) for thermally treated PAN nanofibres at 700, 1000, and 2800 °C, respectively (seen in Figure 2-6), there was no large degradation of capacity as a function of the discharge current density 134 compared to the conventional graphite 136 (Figure 2-7).  Composite carbon nanofibres, e.g. electrospun silicon nanoparticle embedded in PAN carbon nanofibres with core-shell structures137, were investigates as anodes for lithium ion battery. It exhibited outstanding cell performance: a gravimetric capacity as high as 1384 mAh/g, a 5 min discharging rate capability while retaining 721 mAh/g, and cycle life of 300 cycles with almost no capacity loss.137 These characteristics make CNFs good candidates for the anode material of high-power lithium-ion batteries (where a high current is critically needed), owing to the greatly reduced lithium-ion diffusion path within the active material 93,134,135       27  In this thesis, we explored the possibility of lignin-based CNF as the lithium ion battery electrodes to assemble the all solid-state battery.  Figure 2-6 Variation of reversible capacities (rate capability) for nanofibre webs thermally treated at 700, 1000, and 2800 °C at discharge current densities of 30, 50, and 100 mA/g, respectively134  (Reproduced with permission from John Wiley and Sons, Inc. )        28   Figure 2-7 Cycle performances with C-rate of untreated natural graphite and Al-treated natural graphite sample. The circle, triangle, and rectangular plot represent 0.2 C, 0.5 C, and 1.0 C rate, respectively. The simple plot and bold one show untreated and treated samples, respectively. (a) Treated 0.2 C, (b) Treated 0.5 C, (c) Treated 1.0 C, (d) Untreated 0.2 C, (e) Untreated 0.5 C, and (f) Untreated 1.0 C 136 (Reproduced with permission from the Electrochemical Society (ECS).)  2.6.3 Application to Actuator Another potential application of nanofibres is in the smart structures such as actuator. In nature, nanofibres have been adopted to construct the actuator system. Actuator systems triggered by water-sorption-induced swelling are widely present in plants. For example, cell walls are able to move as a result of water absorption and evaporation. The major part of plant cell wall is composed of cellulose nanofibres and are embedded in a hygroscopic matrix containing hemicelluloses and lignin. The basis for the differential swelling of different parts of the tissue is the intricate structure of the plant cell wall 138,139. The anisotropic distribution of       29  swelling stresses in the cell wall lead to the movement of cell wall 140. Many actuation systems in plants have the common feature that the movement is generated by a differential swelling of different parts of the tissue, similar to the function of a bimetallic strip measuring temperature 140.     An actuator is a mechanical device used for the purpose of inducing strain into a system in order to generate motion, change its shape or to compensate disturbing vibrations.141  Traditionally, based on the energy sources for actuation, responsive polymeric materials can be divided into  three types, electroactive polymer, light- or thermal- responsive elastomer, and pH- or solvent-responsive gels.142 The material development for water-sorption-induced swelling for actuation is in progress142. Researchers in the area of smart structures such as actuator have been trying to overcome the limitation of small strains or small forces produced by smart materials; furthermore, they are susceptible to severe circumstances and involve complex preparation such as multi-step lithographic processes or using expensive synthetic polymers such as polypyrrole (PPY)142 or poly(3-cyanomethyl-1-vinylimidazolium bis(trifuoromethanesulfonyl)imide) and carboxylic acid-substituted pillar arene 143.  In this thesis, we study the possibility to develop the moisture-driven actuator from lignin nanofibres.         30  Chapter 3 : Scope and Objectives This thesis will work towards to narrowing the knowledge gap between how to overcome and take advantage of complex lignin chemical structures and enable functionalization of lignin fibres for advanced functional applications. This study explores the feasibility of creating multifunctional lignin materials in nanofibre form to construct a material platform for the development of value-added products. The specific objectives of this dissertation are: Objective 1: To demonstrate the feasibility of functionalizing lignin nanofibres at the fibre architecture level, fibre level, and molecular level to add desired functionality via electrospinning, thermostabilization and carbonization. Chapter 4 will elaborate functionalizing lignin nanofibres at the various levels to add desired functionality via electrospinning, thermostabilization and carbonization. Specific functions will be added to electrospun lignin nanofibres at three different levels such as molecular level, fibre level, and fibre assembly level. At the fibre level, we will demonstrate, in section 4.4.1, the feasibility of fabricating composite carbon nanofibres from lignin impregnated with iron acetylacetonate (IAA) to impregnate functional properties. The fabrication method will involve “in-situ particle synthesis” using IAA as precursor to incorporate the nanoparticles. We will then track changes in the chemical structure of lignin fibre using an array of characterization methods, including SEM, high resolution TEM, and Raman spectroscopy. The composition and the crystal structures of the in-situ synthesized nanoparticles will be studied by EDX and XRD. Moreover, we will determine the influence of IAA salts on thermal, magnetic, mechanical flexibility and electrically conductive properties of lignin composite fibres.         31  With the knowledge of above composite nanofibres of lignin, “architecture-designed” lignin-based nanofibres with 3-D interconnected network structures will be constructed to demonstrate functionalities added to lignin nanofibres at the fibre assembly level and molecular level. Section 4.4.2 will present the fabrication and characterization of architecture-designed nanofibre by blending fractions F1-3 and F4. The effect of blending F1-3 on the formation of 3-D architecture will be studied. We will characterize the morphology, chemical structure, and electrical conductivity of the architecture-designed fibres.  Furthermore, in section 4.4.3, architecture-designed composite carbon nanofibres will be prepared through blending system and sonication system, and will be characterized by SEM and TGA. We will verify the fibre formation mechanism by comparing these three types of multifunctional fibres. Objective 2: To demonstrate the feasibility of applying multifunctional lignin nanofibres for advanced applications Using the previously functionalized lignin nanofibres, we will investigate using lignin-based composite carbon nanofibres for electromagnetic interference shielding (Chapter 5) and for lithium ion batteries electrodes (Chapter 6). Furthermore, we will investigate functionalized nanofibres for actuator applications (Chapter 7).  Chapter 5 will focus on using flexible lignin/iron oxide carbon nanofibres with electrical conductivity and magnetic properties for electromagnetic interference shielding applications. Shielding performance and the shielding mechanism of lignin based carbon nanofibre will be studied. The performance will be compared with conventional petroleum-based carbon nanofibre. Chapter 6 will present the application of lignin/iron oxide carbon nanofibre as the       32  lithium ion batteries electrodes. Flexible lithium ion batteries will be built using lignin/iron oxide carbon nanofibre-based anodes and tested. Chapter 7 will illustrate the actuating phenomenon from lignin nanofibres which are simultaneously functionalized at the molecular level and fibre assembly level. We will also study its actuating mechanism.          33  Chapter 4 : Fabrication and Characterization of Multifunctional Lignin Nanofibre 4.1 Introduction This chapter demonstrates the feasibility of functionalizing lignin nanofibres to add desired functionality by electrospinning, thermostabilization and carbonization.  It is challenging to spin lignin into nanofibres without pre-treatment due to its heterogeneous 3-D branched chemical structure46. Lignin fractionation facilitates the extraction of the high molecular weight part of lignin and improves the ability of fibre spinning51,52. In this study, fractionation of lignin was carried out to fabricate multifunctional lignin nanofibres, followed by electrospinning, thermalstablization and carbonization.  To fabricate multifunctional lignin nanofibres, three strategies were employed to (1) develop composite lignin carbon nanofibres, (2) construct architecture-designed lignin nanofibres, and (3) create architecture-designed composite carbon nanofibres.  Firstly, lignin-based composite carbon nanofibres were prepared by electrospinning and subsequent heat treatment using the 4th fraction F4. F4 was selected due to the good spinablility and the processing parameters of electrospinning and carbonization of F4 into carbon nanofibres have been established in the previous studies51,52,90. But the conditions for processing composite carbon nanofibres using F4 are still unknown. To incorporate nanoparticles into lignin carbon nanofibres, in-situ synthesis method will be used. The traditional approach to incorporate nanoparticles into a composite material relied on direct dispersion such as sonication dispersion. The nanoparticles typically aggregate, which reduces the desired property within the nano dimension. However, the in-situ synthesis method will make it possible to manipulate the       34  dispersion of nanoparticles to build a homogenous composite fibre, as reported in the literature 144–148. Iron acetylacetonate was selected as the precursor for nanoparticles based on previous work in which polyacrylonitrile (PAN) solution containing the iron oxide precursor iron (III) acetylacetonate (AAI) was electrospun and thermally treated to produce electrically conducting, magnetic carbon nanofibre mats with hierarchical pore structures 149.  Specifically, this chapter illustrates an example of lignin composite carbon nanofibre with in-situ synthesized nanoparticles through thermal decomposition of iron acetylacetonate (IAA) within the matrix of lignin electrospun fibres. To track the carbon structural changes of the lignin carbon nanofibres by adding IAA, Raman will be used. Phase structures and composition of in-situ synthesized nanoparticles will be studied by XRD and EDX. To determine the influence of IAA salts on thermal properties of lignin composite fibres, TGA will be used to analyze the samples. The electrical conductivity and magnetic properties will be characterized. The flexibility of lignin carbon nanofibre will be characterized by the bending test. Based on the above knowledge, next, architecture-designed nanofibre involves highly customized attention to the formation of 3-D interconnected structures within the thermalstablized nanofibres and carbon nanofibres. Architecture-designed nanofibres will be fabricated by blending relatively low molecular weight F1-3 and the relatively high molecular weight F4.  In the preliminary study, 3-D interconnected architecture was formed using these two blends51,52. However, the effect of F1-3 on the fibre structure and properties was not explored in depth. Therefore, the formation mechanism of the 3-D interconnected architecture will be investigated.       35  With the knowledge of above two types of multifunctional nanofibre of lignin, architecture-designed composite nanofibres will be prepared by blending method and sonication method. The resultant fibre morphology and thermal properties will be used to verify the role of IAA and F1-3 on the formation mechanism of composite fibre and 3-D interconnected architecture. 4.2 Materials  Softwood kraft lignin (SKL, Indulin-AT) was purchased from Meadwestvaco (Glen Allen, VA, USA). Poly (ethylene oxide) (PEO, Mv = 9 x 105 g/mol) and iron (III) acetylacetonate (IAA, ≥99.9% trace metals basis), triton X-100 (contains less than 3% Polyethylene glycol) were purchased from Sigma-Aldrich. N,N-dimethylformamide (DMF), methanol, and methylene chloride were all  obtained from Fisher Scientific. Fe3O4 nanoparticles (20~30 nm) was purchased from Nanostructured and Amorphous Materials, Inc..  4.3 Methods 4.3.1 Lignin Fractionation  Softwood kraft Lignin (SKL) is a heterogeneous mixture of lignin fragments containing a variety of chemical structures. Fractionation was performed to divide SKL into less heterogeneous fractions. Fractionation was achieved according to solubility by successive extractions with organic solvents.  In comparison with unfractionated lignin, lignin obtained from the fractionation process had a narrower molecular weight distribution 47,48,150.   According to the previously reported process 150, SKL was washed with hydrochloric acid (pH = 2) five times and subsequently washed with methanol twice and mixed methanol/dichloromethane (7:3 by volume) twice. The 1st, 2nd and 3rd fractions (F1-3) and 4th       36  fraction (F4) were then collected for electrospinning and characterization.  Figure 4-1 illustrates the schematic of the lignin fractionation process.  Figure 4-1 Softwood kraft lignin fractionation process150  4.3.2 Fabrication of Lignin-based Electrospun fibres  4.3.2.1 Preparation of Lignin-based As-spun Fibres Electrospinning solutions were prepared as follows. In the solutions, PEO was added to facilitate the subsequent electrospinning 46. The weight ratio of lignin and PEO was 99:146. Each solution was electrospun into nanofibre mats on a drum Electrospinning Unit (Kato Tech Inc., Japan). The electrospinning voltage was 17 kV, the pump rate was 0.097 mm/min and the distance between the nozzle and collector was 15 cm. Lignin nanofibres mat of F4 or F1-3 were obtained from solutions of 25, 30 and 35 w.t. % F4 or F1-3 in DMF. F4-PEO-DMF or F1-3-PEO-DMF solution were prepared by adding lignin and PEO into DMF and heated to 80 ˚C for 2 hours, cooled to room temperature for electrospinning.       37  Composite nanofibres mats were obtained from solutions containing IAA salts which were prepared by first dissolving various amounts of IAA in DMF, followed by the addition of F4 and PEO into DMF. The weight of IAA salts were 1%, 3%, 5%, 10% and 20% of the weight of F4, respectively. Each IAA-F4-PEO-DMF solution was heated and cooled as described above for electrospinning. Architecture-designed lignin nanofibre mats were prepared using various amounts of the mixture of F1-3 and F4 dissolving in PEO-DMF solutions (F4: F1-3 = 7:3, 6:4 and 5:5 by weight, respectively). The F1-3-F4-PEO-DMF solutions were treated as all other solutions for electrospinning. Architecture-designed composite nanofibre mats were prepared in two ways, (1) using the blending system, and (2) using the sonication system. For the blending system, various amounts of IAA was first dissolved in DMF then F4/F1-3/PEO ((F4+F1-3): PEO = 99:1 by weight) was added to the solution (IAA/ (F4+F1-3) = 3% by weight). The IAA-lignin-PEO-DMF solution was treated as all other solutions for electrospinning. For the sonication system, various amounts of Fe3O4 nanoparticles were dispersed in DMF by sonication. Surfactant triton X-100 (mass of surfactant = mass of Fe3O4) was also added to DMF to better disperse the Fe3O4 nanoparticles. Sonication was conducted in the bath sonicator (Branson Bransonic® 3510 5.5L MT UltraSonic Bath Cleaner) for 6 hours. Subsequently, F4 (mass of Fe3O4 nanoparticles =3%, 5% 7% of the mass of F4) was added to the dispersion of Fe3O4/DMF and sonication continued until F4 was dissolved. The solutions were cooled to room temperature and electrospun with the same voltage, follow rate and distance as above.       38  4.3.2.2 Thermostabilization of Lignin-based As-spun Fibres The as-spun fibre mat was oxidized in air in a gas chromatography oven (Hewlett Packard HP 5890 Series II). Stabilization of the as-spun fibres was performed by heating the fibres to 250 ˚C in air at a heating rate of 1, 3 or 5 ˚C/min and held for 1 hour, then cooled down to room temperature. All the thermostabilization was conducted at 250˚C based on previous research results 8,51,52,90.  4.3.2.3 Carbonization of Lignin-based Thermostabilized Fibres Carbonization of thermostabilized lignin electrospun fibres was achieved by heating the thermostabilized fibres to 700, 800, 900 or 1000 ˚C at a rate of 10˚C/min in a nitrogen atmosphere in a tube furnace (GSL1100X tube furnace, MTI corp.). Fibres were held for 1 hour at the maximum temperature, then cooling down to room temperature. 4.3.3 Characterization of Lignin Nanofibres 4.3.3.1 Characterization of Fibre Morphology and Structure  Basic scanning electron microscopy (SEM, Hitachi S-3000N), and transmission electron microscopy (TEM, Hitachi H7600) were used to characterize fibre morphology and structure. More advanced imaging techniques were also used, namely: high resolution TEM (HRTEM), selected area electron diffraction (SAED) and high-angle annular dark-field (HAADF) images as well as energy-dispersive X-ray (EDX) mapping were made using an FEI TecnaiTM Osiris scanning transmission electron microscope (STEM).        39  Wide-angle X-ray diffraction (WXRD) was performed with a Rigaku (Japan) S-3000N Multiplex X-ray diffractometer at 40 kV and 20 mA with a Ni-filtered Cu Kα1 radiation (λ=1.542 Å), and scanned at a rate of 0.08°/min. 4.3.3.2 Chemical Characterization of Lignin Nanofibre Mats X-ray Photoelectron Spectroscopy (XPS) is a method for analyzing the chemical composition of the outermost surface of a sample, 2-10 nm deep. The XPS measurements were performed using an Omicron XPS with energy analyzer EA125 with Mg K-alpha X-ray. A survey scan was done with energy 50eV, followed by a narrower scan with an energy 20eV. Raman spectra were recorded on a RM1000 Raman microscope system (Renishaw, Gloucestershire U.K) equipped with a 785 nm diode laser. Three samples for each condition were tested and the reported results are the average. The disorder (D) band and graphitic (G) band from Raman scattering were fitted into a Gaussian-Lorentzian hybridized function. 4.3.3.3 Thermal stability of Lignin Nanofibre Mats Thermogravimetric (TGA) analysis (TA Instruments Q500) was conducted with 5~10 mg samples heated with a rate of 10˚C/min under nitrogen. 4.3.3.4 Bending Flexibility of Lignin Carbon Nanofibre Mats  The flexibility of lignin carbon nanofibres mats was characterized by the electrical resistance change of the fibre mat in the bending test (Figure 4-2). The experimental customized bending system with in-situ measurement of the electrical resistance and kept on bending the fibre mats from vertical plane to specific angle (110˚) (radius of curvature ~0.6 mm) for       40  customized cycles (1500 cycles). Each cycle was set for 2 seconds. Total testing time was 3000 seconds. The specimens are 2 cm in length and 5 mm in width.    Figure 4-2 the custom-made device for bending test 4.3.3.5 Electrical property of Lignin Carbon Nanofibre Mats  The two-point probe method was used to measure electrical conductivity (σ).  Fibre mats with a dimension of 1.5 cm in length and 5mm in width were painted at both end with silver paint (Ted Pella, Inc. Redding, CA USA) and fixed on glass slides. Conductivity σ (S/cm) was calculated based on the measured R (Ω) and the dimensions of the sample using the following equation. 𝐶𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦 (𝜎) =  𝐿𝑒𝑛𝑔𝑡ℎ (𝐿)𝑊𝑖𝑑𝑡ℎ (𝑊) × 𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠(𝑇) × 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒(𝑅) Length (L) was taken as the distance between the two probes in cm, width (W) was the sample width in cm, and thickness (T) was the thickness of the sample measured using a caliper. Three repeats for each condition were tested and the reported results are the average.       41  4.3.3.6 Magnetic property of Lignin Carbon Nanofibre  A Superconducting Quantum Interference Device (SQUID) was used to measure the magnetic moment (emu) as a function of applied magnetic field (Oe) at 300K. The saturation magnetization and remnant magnetization were calculated by the ratio of the measured magnetization to the quality of the sample. Three repeats for each condition were tested and the reported results are the average. 4.4 Results and Discussions 4.4.1 Composite Carbon Nanofibre from Lignin  4.4.1.1 Morphology of Electrospun Composite Nanofibres In this section, we used the electrospun composite nanofibres as an example to demonstrate adding functions at the fibre level. First, we investigated the effect of solution concentration of lignin (F4) on the morphology of the electrospun fibres and electrospun composite fibres. Electrospun fibres from lignin (F4+PEO) solutions (25%, 30%, and 35%,) were compared to a second set of the electropsun composite fibres using the solutions with identical concentrations of F4, but spun with 3% IAA loadings. The SEM images in Figure 4-3 show that the F4 was able to be spun into fibres without droplets at a concentration as low as 25%, but adding IAA salts resulted in the critical concentration for fibre formation without droplets increased up to 35% (Figure 4-4).  With the addition of IAA, a number of droplets formed on the as-spun fibres at lower solution concentration (25% and 30%).          42      Figure 4-3 SEM image of F4 as-spun nanofibre obtained from F4 solutions with different concentrations (a) 25%, (b) 30% and (c) 35%     Figure 4-4 SEM images of electrospun fibres obtained from F4 solutions containing 3% IAA with different lignin concentrations: (a) 25%, (b) 30% and (c) 35%  This phenomenon may be attributed to IAA salts dismantling the supramacromolecular complexes in lignin. There are pronounced association (non-covalent and non-hydrogen-bonding attractive association) interactions between individual molecular kraft lignin species and these supramacromolecular complexes are responsible for the cohesiveness of kraft-lignin-based materials151. The addition of salts may weaken these non-covalent and non-hydrogen-bonding attractions between individual molecular kraft lignin. This effect has been demonstrated using lithium chloride salts152. Through the addition of salts such as lithium chloride, lignin association can be eliminated and monomodal molecular weight distribution profiles obtained152. Therefore, a b c a b c       43  the reduction of association effect results in less entanglement leading to the increase of solution concentration to form uniform fibres.          Figure 4-5 SEM images of electrospun fibres from 35% F4 solutions with different IAA loadings amount: (a) 0%, (b) 1 %, (c) 3 %, (d) 5%, (e) 10 % and (f) 20%  Next, we assessed the IAA content effect on the formation of electrospun fibres.  Figure 4-5 shows the electrospun fibres from 35% lignin solutions containing different IAA content, 1, 3, 5, 10 and 20%. Regardless of the IAA content, electrospun fibres from 35% solutions were uniform. Therefore, 35% lignin solutions with and without IAA were selected for fabricating non-composite fibres and composite fibres (with 1, 3, 5, 10 and 20% IAA). 4.4.1.2 Morphology of Thermostabilized and Carbonized Composite Nanofibres  We thermostabilized the above electrospun fibres to enable lignin to maintain a fibre form during the subsequent carbonization. Three heating rates, 1, 3, and 5 ˚C/min, were tested to a b c d e f       44  thermalstablize the fibres with 3% IAA. These thermostabilized fibres were also able to keep as-spun fibrous structure with the above heating rate (Figure 4-6). Moreover, we explored the role of IAA on thermostabilization of electrospun fibres with slow heating and fast heating treatment, respectively. Electrospun fibres from solutions of IAA-F4 with 0, 1, 3, 5 10 and 20% IAA were thermostabilized at 250˚C in air with a heating rate of 1˚C/min and 5˚C/min for 60 min (Figure 4-7 and Figure 4-8). The SEM images show that the thermostabilized fibres kept as-spun fibrous structure, but with smaller fibre diameter.     Figure 4-6 SEM images of thermostabilized lignin electrospun fibres from 35% F4 solutions with 3% IAA with heating rats of (a)  1 ˚C/min, (b) 3 ˚C/min and (c) 5˚C/min to 250˚C for 60 min   Subsequently, thermostabilized fibres were carbonized in nitrogen at high temperature. Typical SEM and TEM images of lignin carbon nanofibre with and without IAA are shown in Figure 4-9. We found that after carbonization, carbon nanofibres and composite carbon nanofibres were successfully fabricated. The original fibre shape retained and nanoparticles were formed in the composite carbon nanofibres.     a b c       45        Figure 4-7 SEM images of thermostabilized lignin electrospun fibres 35% F4 solutions with (a) 0 %, (b) 1 %, (c) 3 %, (d) 5 %, (e) 10 % and (f) 20% IAA  treated with a heating rate of 5˚C/min to 250˚C for 60 min          a b c d e f       46         Figure 4-8 SEM images of thermostabilized lignin electrospun fibres 35% F4 solutions with (a) 0 %, (b) 1 %, (c) 3 %, (d) 5 %, (e) 10 % and (f) 20% IAA  treated with a heating rate of 1˚C/min to 250˚C for 60 min  The effects of carbonization temperature and IAA concentration on fibre diameters of electrospun carbon nanofibres were preliminary examined. Firstly, carbonization temperature effect was illustrated. The fibre diameter of the lignin composite carbon nanofibre (3% IAA/F4 thermostabilized electrospun fibres with heating rate of 1˚C/min) thermostabilized at 250 ˚C and carbonized at 700, 800, 900 and 1000˚C. The samples are denoted as 3Atsb, 3A700, 3A800, 3A900 and 3A1000. Figure 4-10 and Figure 4-11 depict the corresponding fibre diameters and nanoparticle sizes. At 3% IAA concentration, the as-spun fibre (3A as-spun) diameters were about ~1400 nm; the fibre diameters of thermostabilized fibres with 3%IAA were about ~ 900 nm; fibres carbonized at 700, 800, 900 and 1000˚C (3A700, 3A800, and 3A900) were about the same (ca. 570 nm), while fibres carbonized at 1000˚C (3A1000) had a slightly larger diameter (ca. 670nm). The average dimension of the nanoparticles got larger, from a few nanometers to a d f e c b       47  100 nm, as the temperature increased from 700 to 1000 ˚C. At the high concentration of 10% IAA, as temperature increased from 900 to 1000 ˚C, fibre diameters were approximately the same (ca. 800 nm), but particle sizes increased from 50 nm to 100 nm. It was found that fibre diameter increased from 570nm to 800 nm with the rise of IAA loading from 3% to 10%. While kept at the same temperature, the particle size remained the same with different IAA loadings. Therefore, fibre diameters are more related to IAA content, whereas particle size is more influenced by temperature.      Figure 4-9 Typical SEM and TEM images of lignin carbon nanofibre (carbonized at 1000˚C) from F4 without IAA (a, b) and lignin composite carbon nanofibre from F4 with 3% IAA (c, d)   a b c d   100nm 100nm       48    Figure 4-10 Effect of thermostabilization  and carbonization process on fibre diameter of 3% IAA/lignin-based composite carbon nanofibres carbonized at 700, 800, 900 and 1000 ˚C (thermostabilized at 250˚C, with ramping rate of 1˚C/min, and held for 60min)    Figure 4-11 Effect of carbonization temperature on particle size of 3% and 10% IAA/lignin-based composite carbon nanofibres carbonized at 700, 800, 900 and 1000 ˚C (thermostabilized at 250˚C, with ramping rate of 1˚C/min, and held for 60min)       49  4.4.1.3 Morphology, Composition and Structure of Nanoparticles       Figure 4-12 Representative HRTEM images of core-shell nanopartiess obtained by in-situ synthesis method within lignin carbon nanofibre prepared from 1% IAA/35%F4, thermostabilized with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C  The detailed morphology and composition of the in-situ nanoparticles synthesised nanoparticles were examined using HRTEM and STEM. A representative sample of electrospun       50  carbon nanofibres with 1% IAA (thermostabilized with 5˚C/min and carbonized at 1000˚C) were discussed here, and more images are provided in the appendix. The structure of porous carbon nanofibre with core-shell nanoparticles was observed for composite carbon nanofibres, as shown in HRTEM images (Figure 4-12).        Figure 4-13 (a) Representative STEM-HAADF image and EDX mapping of  (b) carbon, (c) iron, (d) oxygen and (e) sulfur of lignin electrospun carbon nanofibre prepared from 1% IAA/35%F4, thermostabilized with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C   a b c d e       51  A detailed characterization of the chemical element distribution within nanofibres was performed to trace the composition of the nanoparticles and nanofibres. This was performed using high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDX) elemental mapping. The technique of HAADF imaging, which is highly sensitive to atomic-number contrast, can be performed on STEM systems, and is commonly performed in parallel with EDX spectroscopy acquisition. In Figure 4-13, the electrospun composite carbon nanofibres were imaged using HAADF-STEM and EDX elemental mapping, respectively. The mapping results reveal the main compositions of nanofibres were carbon, iron, oxygen, and sulfur. Elemental analysis was conducted on the lignin CNFs using Carlo Erba Elemental Analyzer EA 1108 and the results showed no sulfur was detected. It is speculated the amount of sulfur is not significant and it is a trace amount. Iron element was seen concentrating in the nanoparticles, while oxygen and sulfur was not present in all the nanoparticles. Conversely, carbon was evenly distributed throughout the entire nanofibres. Moreover, it is observed that nanoparticles were not aggregated along the nanofibre.    Figure 4-14 Representative XPS spectra of electrospun carbon nanofibre with 20% IAA thermostabilized with 5˚C/min and carbonized at 1000˚C: (a) survey (b) Fe 2p a b   719 eV 711.3 eV 724.3 eV 709.80 eV 707.26 eV       52  Future analysis of elemental composition, including the chemical states of each element, was performed by XPS. XPS can be used to detect the surface depth of samples about 10nm.  Figure 4-14 (a) shows the survey spectrum (0-1100 V).  The C(1s) spectra have overlapping peaks near 288 eV. O(1s) spectra possesses a peak near 531 eV. Fe(2p3/2) and Fe(2p½) shows two peaks. Figure 4-14 (b) shows the XPS spectrum of Fe 2p, where two peaks located at 711.3 and 724.3 eV and a satellite peak at 719 eV which are in good agreement with the values reported for γ-Fe2O3 in the literature 153,154. A key characteristic which distinguishes γ-Fe2O3 from Fe3O4 is the presence of the satellite peak at a binding energy of 719.0 eV 153.  Fe atoms (707.26 eV) and Fe3C (709.8 eV) are also present in the sample. Our results indicated that the particle surface is iron oxide and in the core of the particles is Fe/Fe3C, which was verified in the XRD results.  The porous structure formation of the lignin-based composite carbon nanofibres is possible due to the inhibition of thermostabilization oxidation of lignin by the transition metal oxide, which is consistent with TGA results. More detailed explanations will be provided in the following sections.  4.4.1.4 XRD Analysis of Crystal Structures of Nanoparticles XRD was used to characterize the crystal structures of the nanoparticles.  Effects of IAA concentration and thermostabilization heating rate on the crystal structure of the nanoparticles within the electrospun carbon nanofibres were investigated (Figure 4-15, Figure 4-16, and Figure 4-17). The detailed analysis and indexing for each sample is listed in the appendix. With a heating rate of 1˚C/min for thermostablization, γ-Fe2O3 nanoparticles and ordered carbon structure were formed in the resultant CNF (carbonized at 1000 ˚C) with 3% IAA (Figure       53  4-15).  γ-Fe2O3 is a typical ferrimagnetic material like Fe3O4. It can be readily magnetized and thus has a high magnetic response when placed in an external magnetic field. These results were supported by additional characterization of the magnetic properties reported in the following section. In composite carbon fibres spun from different concentrations of IAA (1, 5, 10 and 20%), we observed characteristic diffraction peaks for iron and iron carbide (Figure 4-15) and amorphous carbon structure were detected.  With a heating rate of 3˚C/min at thermostabilization stage, we observed characteristic diffraction peaks for ordered carbon, iron and iron carbide for CNF with 3% IAA (seen in Figure 4-17). With a heating rate of 5˚C/min at thermostabilization stage, we observed characteristic diffraction peaks for iron and iron carbide for CNF with IAA content from 1% to 20% (seen in Figure 4-16). A trend is clearly shown that relatively more iron carbide phase than iron phase was present by increasing the IAA amount. These results are the consequences of the different reactions of nanoparticles within the matrix of lignin based carbon nanofibres at different conditions. During the carbonization process, H2, CO, CO2 were generated and amorphous carbon was formed.  Fe2O3 formed from IAA in the thermal station stage would mostly be reduced in the carbonization process by emitted gas and carbon to products like Fe3O4 and Fe, and may also result in Fe3C formation121. The possible reactions might be Fe2O3 + CO →Fe +CO2 and 3Fe +C→ Fe3C. It is proposed that for the thermostabilization process, thermostabilization reactions get depressed at larger extent with more IAA. Subsequently, less stable carbon structure was formed in the thermostabilization and carbonization process (verified by  TGA results), therefore, more CO or H2 generated and more iron oxide gets reduced by these       54  gases and reacts with carbon. Therefore, relatively more iron carbide phase than iron phase was present by increasing the IAA amount.  By contrasting results from different heating rate, we found that at slower heating rate with proper amount of IAA, the nanoparticles of iron oxide were generated and promoted the formation of ordered carbon structure; whereas lower or higher amount of IAA, iron and iron carbide nanoparticles were formed and no ordered carbon structure was detected by XRD. The significance of this in-situ synthesise method is that by simply tuning the heating rate of thermostabilization and IAA concentration, the nanoparticles composition and crystal structure are able to be manipulated. Iron-based nanoparticles can have useful magnetic and catalytic properties, which is critical for the advance applications.     Figure 4-15 XRD pattern of CNF obtained from electrospun fibres with different amount of IAA (1, 3, 5, 10 and 20%) with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C       55   Figure 4-16 XRD pattern of CNF obtained from electrospun fibres with different amount of IAA (1, 3, 5, 10 and 20%) with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C  Figure 4-17 XRD pattern of CNF obtained from electrospun fibres with 3% IAA with thermostabilization  heating rate of 1, 3 and 5˚C/min at 250˚C for 60min and carbonized at 1000˚C       56  4.4.1.5 Raman Analysis of Carbon Structure of Composite Carbon Nanofibre Raman spectroscopy was used to characterize the structural changes of carbon occurring in the carbonization process. Raman spectra consisted of a broad D-band at around 1310 cm-1 and a G band at around 1580 cm-1 (Figure 4-18). The D-band corresponds to the breathing modes of 6-carbon aromatic rings, while the G-band corresponds to in-plane bond stretching motion of pairs of C sp2 atoms in both rings and chains.155 ID represents the intensity of the D-band, and IG represents the intensity of the G-band. The R=ID/IG ratio, full width at half maximum (FWHM) and band positions are summarized in Table 4-1.   Figure 4-18 Raman spectra of 3% and 10% IAA/lignin-based composite carbon nanofibres carbonized at 700,  800,  900 and 1000 ˚C (thermostabilized conditions : 1˚C/min, 250˚C and 60 min)             57   Effects of carbonization temperature and IAA concentration on resultant carbon structure were studied. At low IAA concentration (3%), the effect of carbonization temperature on carbon fibre structure was investigated and it was found that R increased from 1.61 to 1.81 with increasing carbonization temperature from 700 to 900 ˚C. Within all the carbonized fibres, pronounced disorder of the carbon structure are present. With the increase of temperature, D and G peak widths decreased (Table 4-1) which indicated an increase in more organized structure was formed. However, R decreased to 1.75 as the carbonization temperature further increased to 1000 ˚C.  This phenomenon contrasted with previous reports of PAN-based CNFs and PAN-based magnetic CNFs, where it was reported that R always decreased with increasing carbonization temperature19,121. For example, Bayat et al. reported that at different loadings of iron oxide nanoparticles, 1 wt.% , 5 wt.%, 10 wt.% , the value of R decreased with increasing temperature from 700 to 900 ˚C 19. Similar results were found in Zhang’s work, where different contents of IAA (2% and 3%) resulted in a drop in R when temperature increased from 700 to 800 ˚C121.  To interpret the above results, it should be noted that the chemical structure of PAN and lignin are quite different. PAN has a more linear and organized structure, while lignin has a 3-D complex branching molecular structure. It is reasonable, then, to expect that after carbonization, PAN would have a more ordered carbon structure, while lignin has a more disordered structure. To further understand the different trends of R between lignin and PAN, we can look at Ferrari’s theory155. In this theory there is a three-stage model for transitions in carbon structure: amorphous carbon to nanocrystalline graphite to graphite, with a corresponding R increase       58  followed by decrease between amorphous and nanocrystalline phases. It is speculated that PAN carbon structure is in the form of nanocrystalline graphite already, and thus the R only decreases19,121. In contrast, lignin-based carbon structures are hypothetically in the range from amorphous carbon to nanocrystalline graphite carbon; hence, R would increase and then decrease. Although lignin-based carbon is less ordered than PAN-based carbon, the structure of lignin carbon is more organized compared to lignin itself.  With the temperature increased from 900 to 1000˚C, at 3% R decreased whereas at 10% R increased. The higher the content of IAA, and the greater FWHM, suggesting a more disordered carbon structure was formed. The decrease of R at 1ow concentration (3%) may be caused by the catalytic effect of IAA in the carbonization stage. Previously, it was shown that the introduction of Fe3O4 by adding IAA, promoted formation of graphitization layers at low IAA content 19,121,149. It was also reported that transition metals such as iron, cobalt and nickel were used as catalysts to grow carbon nanofibres156–158.  At 10 % (10A900 and 10A1000) R increased with increasing temperature, which may be attributed to the hindered catalytic effect of IAA on carbonization121. In the literature, when IAA content is excessive, the formation of graphitized layers is inhibited. It has been reported that incorporation of a metal into the disordered carbon fibre matrix breaks the sp2 carbon bonds and formation shorter carbon chains159. Our results suggest that the carbon structure was likely in the transition stage from the amorphous carbon (3A900), to the nanocrystalline graphitic carbon for the lower IAA loading (3A1000), while the higher (10%) loading, in the amorphous carbon stage. This result is consistent with our XRD, and TGA findings.        59  Table 4-1  The intensity ratio (ID/IG), as well as the full width at half maximum (FWHM), and position 3% and 10% IAA/lignin-based composite carbon nanofibre carbonized at 700, 800, 900 and 1000 ˚C. IAA concentration Temperature R=ID/IG Wave number (cm-1) FWHM (cm-1) D band G band D band G band 3A 700 1.61 1314 1581 239 138 3A 800 1.72 1312 1580 229 153 3A 900 1.84 1314 1579 229 167 3A 1000 1.75 1301 1585 219 146 10A 900 1.82 1315 1580 246 154 10A 1000 1.86 1316 1582 208 167  4.4.1.6 Characterization of Thermal Stabilities of Composite Carbon Nanofibres In order to understand the formation mechanism of composite carbon nanofibres and the role of IAA on the structures of lignin-based CNFs, thermogravimetric analysis (TGA) was carried out. We investigated the carbonization of lignin thermostabilized nanofibres under nitrogen atmospheres using TGA (Figure 4-19 and Figure 4-21). The TGA curve in air can be divided into three steps according to the mass loss rate. In the first step, the thermostabilized lignin fibre without IAA lost very minor portion of mass until 250°C. In contrast, the thermostabilized lignin fibre by increasing the amount of IAA lost slightly larger portion of weight up to 250°C. This suggests that uncompleted of the thermostabilization stage in which IAA salts provided a sterically hindered environment to the condensation and cyclization reactions and restrained the mobilities of the F4 components..  In the second step, the rate of mass loss rate accelerated, as seen in the sharp drop of the curve and continued as the temperature increased to ~600˚C. AAI decomposition just accounted       60  for a small percentage of weight loss, thus the most substantial loss in 1%, 3%, 5%, 10% and 20% samples compared with lignin sample may result from the dehydrogenation and the volatilization of the gases being formed from the incompletely oxidized functional groups due to inhibition effect of AAI on the stabilization reactions.   Figure 4-19 Thermogravimetric analysis of thermostabilized electrospun fibres with different amount of iron salt (0, 1, 3, 5, 10 and 20%) with a heating rate of 1 ˚C/min to 250 ˚C for 60 min         61   Figure 4-20 Derivative of weight loss as a function of temperature for thermostabilized electrospun fibres with different amount of iron salt ( 0, 1, 3, 5, 10 and 20%) with a heating rate of  1˚C/min to 250 ˚C  for 60 min  In the final step, the rate of mass loss became slower and steadier. Considering the high thermal stability of metallic oxides, the peaks after 600˚C represented the reduction of Fe2O3 by carbon monoxide gas which may be produced by the carbonization of lignin. During the carbonization process, H2, CO, CO2 were generated and amorphous carbon was formed.  Fe2O3 formed from IAA in the thermal station stage would mostly be reduced in the carbonization process by emitted gas and carbon to products like Fe3O4 and Fe, and may also result in Fe3C formation121. The possible reactions might be Fe2O3 + CO →Fe +CO2 and 3Fe +C→ Fe3C. The residual weight of lignin fibre without iron salt at 800 °C was higher than that of lignin nanofibres with IAA salts, which also indicates the hindering effect of IAA on thermostabilization and carbonization reactions.        62    Figure 4-21 Thermogravimetric analysis of thermostabilized electrospun fibres with different amount of iron salt ( 0, 1, 3, 5, 10 and 20%) with a heating rate of  5˚C/min        63   Figure 4-22 Derivative of weight loss as a function of temperature for thermostabilized electrospun fibres with different amount of iron salt (0, 1, 3, 5, 10 and 20%) with a heating rate of 5˚C/min Comparison to the non-composite fibres, for both heating rate of 1 and 5˚C/min, increasing the amount of IAA from 1 to 20%, the temperature for maximum weight loss (Tmax) shifted to lower value (Figure 4-20 and Figure 4-22). Interestingly, the sample with 3% with a heating rate 1 ˚C/min Tmax shifted to higher temperature (Figure 4-20). This suggested the catalytic effect on the thermostabilization reactions from 3% IAA with 1˚C/min as the heating rate; however, the rest loadings and conditions among the tested range inhibited the thermostabilization reactions.  4.4.1.7 Characterization of Electrical Conductivity and Magnetic Properties of Composite Carbon Nanofibres The addition of magnetic nanoparticles through in-situ synthesis method transferred magnetic properties to the lignin nanofibres. This was confirmed in the observations from        64  SQUID test (Figure 4-23). The M-H curves demonstrate the magnetic properties of materials including the saturation magnetization (Ms); remnant magnetization (Mr) and coercivity (Hc). Figure 4-23 exhibits the hysteresis in the corresponding samples. The magnetic properties of lignin-based magnetic carbon fibres (Ms = 1.8~7.4 emu/g, Mr = 0.15~2.21 emu/g and coercivity = 108~125 Oe) were similar to that of PAN based magnetic carbon fibres19,121,149.  Electrical conductivity of lignin-based magnetic carbon nanofibres (mCNFs) was compared to that of  PAN based mCNFs, 2~5 S/cm versus 0.38~1.2 S/cm19,121,149, respectively. The electrical conductivity and magnetic properties are summarized in Table 4-2.    Figure 4-23 Representative magnetic hysteresis loops of 3% and 10% IAA/lignin-based composite carbon nanofibre carbonized at 700, 800, 900 and 1000 ˚C (Inset graph: enlarged range of the magnetic field from -250G to 250G )        65  Correlations between electrical conductivity, magnetic properties and fibre structures were discussed based on the electrical conductivity and magnetic properties (Table 4-2) and R in Table 4-1 in section 4.4.1.6. Electrical conductivity and magnetic properties (Ms and Mr) of 3A700, 3A800, 3A900 and 3A1000 increased and then decreased with increasing temperature of carbonization.  For 10A900 and 10A1000, electrical conductivity improved with increasing temperature, consistent with the change in R.  Electrical conductivity mainly depended on the fibre carbon structure which was affected by IAA concentration. The increase in electrical conductivity was caused by iron oxide mediated enhancement of conductivity by catalytic graphitization of carbon. The decrease in electrical conductivity may be attributed to obstruction of the conductivity paths by non-conducting separation within the fibres. Therefore, the inhibition of the catalytic reaction by high levels of IAA resulted in the 10A900 being less conductive than the 3A900.  Table 4-2 Ms, Mr, Hc and average particle size of 3% and 10% IAA/lignin-based composite carbon nanofibres carbonized at 700, 800, 900 and 1000 ˚C (250-1-60)  Nanoparticle   size (nm) Ms (emu/g) Mr (emu/g) Hc (Oe) Conductivity (s/cm) 3A700 < 10 1.26 0.0077 18 0.21±0.04 3A800 10 ~ 30 1.85 0.09 20 0.99±0.14 3A900 ~50 1.86 0.31 110 5.01±0.19 3A1000 ~100 1.23 0.15 120 4.31±0.16 10A 900 ~50 6.73 1.77 108 2.38±0.53 10A1000 ~100 7.43 2.21 125 4.68±0.96        66  Our results in Table 4-2 demonstrate that the amount of IAA present had a stronger effect on Ms and Mr than the carbonization temperature, though the temperature also factored. Ms and Mr increased with increasing IAA content. Hc was more directly correlated to nanoparticle size. As temperature increased, the size of the nanoparticles increased from a few nanometers to a hundred nanometers and Hc changed from almost zero to 125 Gauss. The related hysteresis is due to the change from a superparamagnetic loop to ferromagnetic loop. The electromagnetic properties of the resultant fibres can be tailored through the control of the IAA loading and carbonization temperature. 4.4.1.8 Characterization of Bending Flexibility of Composite Carbon Nanofibre Mats Lignin composite carbon nanofibre mats were very flexible (Figure 4-24, b) in comparison to the non-composite lignin carbon nanofibre mats (Figure 4-24, a). The extent of its flexibility was characterized by bending test, where only minor changes in the resistance of the fibre mats with various amount of IAA (1%, 3%, 5%, 10% and 20%) were observed after bending at 110˚C over 1500 cycles (Figure 4-25). The lignin carbon nanofibres without IAA salts were not flexible.        67    Figure 4-24 Representative photos of (a) non-flexible carbon nanofibre mats and (b) flexible lignin carbon nanofibre mats with IAA.  The flexibility of the composite carbon nanofibre can be explained by the amorphous carbon structure formed during the uncompleted thermostabilization and carbonization reactions and the increase of inter-spacing of carbon atoms due to the presence of iron, iron oxide or iron carbide nanoparticles. The resultant lignin-based composite carbon nanofibres are flexible, electrical conductive and magnetic active, indicating their potential applicability in flexible electronics related areas. a b       68   Figure 4-25 Resistance change in the process of bending test for the flexible lignin composite carbon nanofibre with different IAA loadings (1, 3, 5, 10and 20%) 4.4.1.9 Summary  This section demonstrates, at the fibre level, electrical functions, magnetic functions and bending flexibility were introduced to lignin nanofibres. Lignin-based composite carbon nanofibres embedded with in-situ synthesized nanoparticles from IAA were successfully prepared via electrospinning, thermostabilization and carbonization. The effects of IAA on the structure and properties of the resultant composite carbon nanofibres were investigated. With 1,5,10 and 20% IAA, composite carbon nanofibres exhibited amorphous carbon structure because the thermostabilization and carbonization process was depressed. In contrast, with 3%       69  IAA, ordered carbon structure was detected for composite carbon nanofibres due to the catalytic effect of IAA on the thermostabilized and carbonized nanofibres. Moreover, the structure of in-situ synthesized nanoparticles can be controlled by simply tuning the heating rate of thermostabilization and IAA concentration. Iron oxide nanoparticles were synthesised within electrospun composite carbon fibres using 3% IAA (thermostabilized with 1˚C/min and carbonized at 1000˚C), whereas iron and iron carbide nanoparticles were formed within electrospun carbon fibres with 1,5,10 and 20% IAA. The electrical conductivity of electrospun composite carbon nanofibres with 3% IAA (thermostabilized with 1˚C/min and carbonized at 1000˚C) was in the range of 5 S/cm, comparable to that of PAN-based electrospun carbon Falso comparable to that of PAN-based electrospun carbon nanofibres. The amorphous structure of lignin and the addition of functional fillers impart bending flexibility to lignin carbon nanofibre mats. The resultant lignin-based composite carbon nanofibres are flexible, electrical conductive and magnetic active, indicating their applicability in electromagnetic related areas. 4.4.2 Architecture-designed Nanofibre from Lignin In this section, we demonstrated adding functions at the fibre assembly level, by designing its architecture through electrospinning the blend of F1-3 and F4. 4.4.2.1 Morphology of Architecture-designed Nanofibre We determined the critical solution concentration for electrospinning each fraction such as F1-3 and F4 into nanofibres. F4 has relatively higher molecular weight and it was able to be spun into fibres at concentrations as low as 25%, as reported in Figure 4-3. But F1-3 has a relatively lower molecular weight, and it required to be spun at higher concentration (35 %) to obtain uniform fibres without droplets (Figure 4-26). We assessed the critical solution       70  concentration for electrospinning of the blend of these two fractions. We found that the 30% solution could be electrospun and thermostabilized into uniform fibres without droplets (Figure 4-27).      Figure 4-26 SEM images of as-spun nanofibres from (a) 30% and (b) 35% solutions of F1-3   Figure 4-27 SEM image of as-spun nanofibres from the 30% solution of the blend of F4 F1-3 (weight ratio 5:5)  The architecture of 3-D interconnected nanofibres was formed via thermostabilizing the electrospun nanofibre from the blend of F1-3/F4 (5:5).  Figure 4-28 c and d shows a representative SEM images of the surface and cross-section of the nanofibre mat with the 3-D interconnected a b       71  architecture (electrospun from 30% solution of F1-3/F4 (F1-3:F4 =3:7) and thermalized with 5˚C/min at 250˚C for 60 minutes). In comparison, the nanofibre mat without this architecture is shown in Figure 4-28 a and b (electrospun from 30% solution of F4 and thermalized with 5˚C/min at 250˚C for 60 minutes). In the process of thermostabilization, fibre interconnection is usually prevented. However, if fibre fusion occurs, it can be used to incorporate functional properties to thermostabilized lignin nanofibres and carbonized lignin nanofibres, which will be discussed in the following sections and chapters.                   72       Figure 4-28 Representative SEM images of the surface (a, c) and cross-section (b, d) of the nanofibre mat with the 3-D interconnected architecture (a, b electrospun from 30% solution of F4 and thermalized with 5˚C/min at 250˚C for 60 minutes; c, d electrospun from 30% solution of F1-3/F4 (F1-3:F4 =3:7) and thermalized with 5˚C/min at 250˚C for 60 minutes)   The formation of fibre architecture was attributed to the plasticization effect of the blended components which have lower glass transition temperature (Tg). F1-3 had a lower Tg (~122˚C, supporting information provided in the appendix) than that of F4 (~222˚C, supporting information provided in the appendix). Thermostabilization was dramatically different between the two SKL fractions tested. Thermostabilized fibres from a solution of 30% F1-3 produced a smooth film even with a very gentle heating rate (0.5˚C/min), whereas thermostabilized fibres formed from a solution of 30% F4 even with harsher ramping of 5˚C/min. The higher thermal c d b a       73  flexibility of F1-3 might allow the lignin molecules to dissociate from each other, while F4 was not able to disrupt intramolecular interactions enough to have a substantial thermal induced flow. In the F4/F1-3 blend systems, the individual F1-3 components are structurally less rigid and more thermally mobile than F4 components51.  Therefore, the addition of F1-3 resulted in to the increase of thermal segmental motion of molecular chains of F4. This plasticization effect is the mechanism for the formation of this interconnection architecture.   Figure 4-29 SEM images of thermostabilized nanofibre (5˚C/min, 250˚C, 60 minutes) from the blend of F4 and actylated-F4 with different blend ratios: (a) 7:3 and (b) 5:5  This mechanism of “plasticization effect” was also verified by electrospinning and thermalstablization the blend of F4 and acteylated-F4.  Acetylated lignins are thermally softened at moderate temperatures due to decreases in strong intermolecular interactions and possess lower Tg. Tg for the acetylated-F4 is about 150˚C (supporting information provided in the appendix). Thermostabilized nanofibre (5˚C/min, 250˚C, 60 minutes) from the blend of F4 and acteylated-F4 with different blend ratios were fused at a large extent at the ratio of 7:3 (Figure 4-29, a) and formed smooth film at the ratio of 5:5 (Figure 4-29, b). a b       74  Controlling the architecture and properties of lignin-based thermostabilized electrospun materials can be achieved by altering the ratio of F4/F1-3 fractions. Thermostabilized fibres containing different ratios of F4/F1-3 have very different morphologies (Figure 4-30). With more F1-3, the fibre interconnection degree was increased due to the plasticization effect of F1-3.       Figure 4-30 SEM images of thermostabilized fibres from 30% solutions containing (a) F4, (b) F4:F1-3 =7:3, (c) F4:F1-3 =6:4 and (d) F4:F1-3 =5:5 with a heating rate of 5˚C/min to 250˚C for 1 hour  Thermostabilized lignin fibres from the blend of F4/F1-3 formed a fibre network, opposed to linear fibres, which survived subsequent carbonization. Figure 4-31 and Figure 4-32 show SEM images of lignin carbon nanofibres maintaining interconnection architecture-designed after carbonization at different temperature from 400, 500, 600, even up to 900 and 1000˚C c d b a       75      Figure 4-31 SEM images of carbonized architecture-designed nanofibres (250˚C-5˚C/min-60 min) from 30% lignin solutions (F4:F1-3=5:5) at (a) 400 ˚C (b) 500 ˚C and (c) 600˚C      a b c       76    Figure 4-32 SEM images of carbonized architecture-designed nanofibres (250˚C-5˚C/min-60 min) from 30% lignin solutions (F4:F1-3=7:3) at (a) 900 ˚C and (b) 1000˚C  4.4.2.2 TGA Analysis of Thermal Properties of Architecture-designed Nanofibre Thermogravimetric analysis was carried out to understand the formation mechanism of architecture-designed carbon nanofibres TGA plots of thermostabilized fibres are shown in Figure 4-33. When the ratio of F4:F1-3 is 6:4, the yield of carbon was higher than that of pure lignin thermostabilized fibres. This resulted from lignins in the F1-3 playing the role of crosslinking agents, promoting the thermostablization reactions to form stable carbon structures and lead to the increase of the carbon yield.  When the ratio was 7:3 or 5:5, the role of F1-3 was to hinder stable fibre formation, which causes the decrease of the carbon yield.   a b       77   Figure 4-33 TGA plots of thermostabilized fibres from F4 and the blend of F4/F1-3 with different ratios (7:3, 6:4 and 5:5) 4.4.2.3 Characterization of Electrical Conductivity Electrical conductivity was characterized to illustrate the functional properties added via design of nanofibre assembly architecture.   Electrical conductivity of the non-bonded (sample 1 in Figure 4-32) and inter-bonded carbon nanofibres (sample 2 and 3 in Figure 4-32) have been characterized and compared Figure 4-34). The conductivity of non-bonded and carbonized at 900˚C (sample1) was about 5 S/cm, while sample 2 with inter-bonded architecture carbonized at 900˚C, increased to 30 S/cm. This was a clear example that the formation of inter-bonding networks within the nanofibre improved electrical conductivity. Sample 3 was a carbon fibre network carbonized at 1000˚C, and had an       78  even higher average electrical conductivity of 55 S/cm. Thus, carbonization temperature can also increase electrical conductivity.  Figure 4-34 Electrical conductivity of non-bonded lignin carbon nanofibres sample 1 (spun from 30%F4 and carbonized at 900 ˚C) and inter-bonded lignin carbon nanofibres sample 2 (spun from 30%F4/F1-3 and carbonized at 900 ˚C) and sample 3 (spun from 30%F4/F1-3 and carbonized at 1000 ˚C)  4.4.2.4 Summary This section illustrates that functions added fibre assembly level to electrospun lignin nanofibres. Carbon nanofibre mats with 3-D interconnected architecture were successfully prepared by blending two fractions of softwood kraft lignin, F4 and F1-3. The formation of fibre architecture may be attributed to the plasticization effect of the blended components which have lower glass transition temperature (Tg) such as F1-3. A new family of multifunctional thermostabilized lignin nanofibres were created with 3-D interconnected network and a number of functional group, which opens up the possibility of advanced applications such as actuator.        79  Also, after carbonization, the electrical conductivity of architecture-designed carbon nanofibres was increased compared with that of the regular lignin-based carbon nanofibres, which enable it to be used for electronic applications.  4.4.3  Architecture-designed Composite Nanofibre from Lignin Going a step further, we constructed the interconnected composite nanofibres from lignin to verify the role of IAA and F1-3. Blending system and sonication system were used, respectively.  4.4.3.1 Blending System We examined the spinning conditions to prepare the architecture-designed composite nanofibre via blending IAA and F4/F1-3. 35% lignin solutions of F4 with 3% IAA and 35% lignin solutions of F4/F1-3 were able to be electropsun into uniform fibres. However, large amount of droplets were formed in the electrospun fibres of 35% lignin solutions (F4/F1-3) with the same iron salts loadings (3% IAA) (Figure 4-35).  This result is consistent with the reported results in the previous sections, the individual addition of F1-3 or IAA lead to the increase of fibre formation concentration. When adding F1-3 and IAA together into the spinning solution, the fibre formation concentration increased further to 40%.  Next, we assessed the thermostabilization conditions to prepare the architecture-designed composite nanofibre by blending system. The thermostabilized fibre (250˚C-5 ˚C/min-60min) from blend of F4 and F1-3 were fused into network with the ratio of 5:5 (Figure 4-30, d). But with the addition of 3% IAA, to form network structure, the blending ratio raised up to 3:7 (Figure 4-36 b), which indicated the role of IAA was inhibiting the bonding of F1-3 and F4. This is consistent with previous observation that in the thermostabilization process, IAA salts provide an       80  extra sterically hindered environment to the curing reactions and restrained the mobilities of the lignin molecules. When the ratio increased further up to 2:8 (Figure 4-36, a), the degree of fibre fusion increased. This is also consistent with previous phenomenon that F1-3 favors the thermal flow and crosslinking of the lignin molecules. TGA results (Figure 4-37) of fibres from the blending system confirmed that the proper amount of F1-3 is helpful for the formation of stable carbon structure and higher yield. Among the tested samples, the one with 3%IAA- F4 /F1-3 (2:8) had highest yield, whereas the yield dropped by decreasing the content of F1-3. This is also consistent with the previous analysis of the role of F1-3.     Figure 4-35 SEM images of electrospun fibres from the blending system of IAA-F1-3-F4 (a) 0%IAA-35% F4 /F1-3 (5:5), (b) 3%IAA-35% F4 /F1-3 (5:5), and (c) 3%IAA-40% F4 /F1-3 (5:5)    a b c a b       81  Figure 4-36 SEM images of carbon nanofibres spun from the blending system of IAA-F1-3-F4 (a) 3%IAA-40% F4 /F1-3 (2:8), and (b) 3%IAA-40% F4 /F1-3 (3:7) and thermostabilized with 5˚C/min and carbonized  at 1000˚C  Figure 4-37 TGA plot of thermostabilized fibres (thermostabilized with 5˚C/min at 250 ˚C for 60 min) from the blending system of IAA-F1-3-F4: 3%IAA- F4 /F1-3 (2:8), 3%IAA- F4 /F1-3 (5:5), 3%IAA- F4 /F1-3 (6:4) and 0%IAA- F4 /F1-3 (10:0) 4.4.3.2 Sonication System We examined the spinning conditions to prepare the architecture-designed composite nanofibre via sonication system. Figure 4-38 displays the SEM images of electrospun fibres from the sonication system. The solution of 30% F4 with 3% Fe3O4  was electrospun into droplets. The solutions of 35% F4 with 3% and 5% Fe3O4 were able to be spun into fibres. When the spinning       82  solutions contained 7% iron oxide, droplets were formed on the electrospun fibres because no sufficient molecular chain entanglement to form uniform fibres. This can be explained that sonication reduced the molecular weight of lignin 160 and the steric hindrance effect of nanoparticles to restrain the molecular chain to entangle. When the molecular weight got decreased, the molecular chain was not sufficient long to be entangled to form uniform fibres and the extra loading of nanoparticles inhibited the entanglement of molecules to from fibres.   Next, we assessed the thermostabilization conditions to prepare the architecture-designed composite nanofibre with the sonication system. Figure 4-39 shows the SEM images of thermostabilized electrospun fibres from 35% F4 with 3% and 5% Fe3O4.  Fibres from both samples were fused together into the network structure with a heating rate of 5˚C/min. Figure 4-40 exhibits the SEM images of 35% F4 with 3% and 5% Fe3O4 electrospun fibres thermostabilized with a heating rate of 1˚C/min. Fibres were able to keep its as-spun fibre form.  This is consistent with previous observation that lower Tg from the lower molecular weight portion favors the formation of interconnected architecture.              83      Figure 4-38 SEM images of electrospun fibres from solutions of (a) 30% F4-3% Fe3O4, (b) 35% F4-3% Fe3O4, (c) 35% F4-5% Fe3O4 and (d)35% F4-7% Fe3O4    Figure 4-39 SEM images of thermostabilized fibres with a heating rate of 5˚C/min from (a) 35% F4-3% Fe3O4 and (b)  35% F4-5% Fe3O4  a b c d a b       84    Figure 4-40 SEM images of thermostabilized fibres with a heating rate of 1˚C/min from 35% F4-3% Fe3O4 and 35% F4-5% Fe3O4  TGA plots (Figure 4-41) shows that the yield of fibres with 3% iron oxide is higher than that of non-composite fibres, while the yield of fibres with 5% iron oxide is lower than that of non-composite fibres. Therefore, it is clear indication that 3% iron oxide acted as catalyst to produce more stable chemical structure and the resultant higher yield; in contrast, 5% iron oxide is an inhibiting agent for the thermostabilization reaction and gave lower yield. These results are consistent with previous observation of the role of iron oxide nanoparticles generated from IAA.  c d       85   Figure 4-41 TGA plot of thermostabilized fibres (250˚C-5˚C/min-60min) from the sonication system of 35% lignin solutions with 0% Fe3O4, 3% Fe3O4, and 5% Fe3O4  4.4.3.3 Summary A comparison of blending and sonication strategies for fabricating architecture-designed lignin based composite carbon nanofibres with the previous two types of lignin carbon nanofibres (composite carbon nanofibres and architecture-designed carbon nanofibres ) confirmed that IAA sterically hindered the thermostabilization  reactions but IAA may as a catalyst with proper amount to form more stable chemical structure, whereas the proper amount of F1-3 was helpful for the formation of interconnected architecture and promoted stable carbon structure formation.       86  4.5 Conclusions We successfully introduced functions into lignin by creating multifunctional lignin materials in nanofibre form. Free-standing and mechanically flexible electromagnetic lignin composite carbon nanofibre mats, architecture-designed thermostabilized nanofibre with large amount of functional groups, architecture-designed carbon nanofibres with relatively high electrical conductivity and architecture-designed composite carbon nanofibres were fabricated and characterized..  The structures and properties of the flexible electromagnetic lignin composite carbon nanofibre mats were characterized.  The effects of IAA on the structure and properties of the resultant composite carbon nanofibres were investigated. We found the structure of in-situ synthesized nanoparticles can be controlled by simply tuning the heating rate of thermostabilization and IAA concentration. The electrical conductivity of electrospun composite carbon nanofibres was ~ 5 S/cm, comparable to that of PAN-based electrospun carbon nanofibres. Magnetic properties of lignin-based electrospun composite carbon nanofibres were also comparable to that of PAN-based electrospun carbon nanofibres. The amorphous structure of lignin and the addition of functional fillers impart bending flexibility to lignin carbon nanofibre mats. The resultant lignin-based composite carbon nanofibres are flexible, electrical conductive and magnetic active, indicating their potential applicability in electronics related areas.  Moreover, architecture-designed thermalstablized nanofibre mats with large amount of functional groups, have been successfully prepared from two fractions of softwood kraft lignin,       87  F4 and F1-3, by electrospinning and subsequent thermostabilization.  It opens up the possibility of advanced applications such as actuator. After carbonization of the architecture-designed thermalstablized nanofibre mats, the electrical conductivity of architecture designed carbon nanofibres was improved in comparison with that of the regular lignin based carbon nanofibres. A new family of multifunctional lignin carbon nanofibres has been created and opens up the possibility to apply lignin to advanced chemical and electrical applications. We investigated the role of IAA and F1-3 for the thermostabilization process. We found that IAA salts provide an extra sterically hindered environment to the curing reactions and restrained the mobilities of the lignin molecules. But blending the proper amount of F13 is helpful for the formation of stable carbon structure and higher yield.           88  Chapter 5 : Flexible Lignin Carbon Nanofibre Application for EMI Shielding  5.1 Introduction Significant electromagnetic interference (EMI) pollution continuously receives great attention because of the booming development of electrical and electronic industries. The strong EMI pollution not only can lead to disturbances on various systems and equipment, but also is potentially harmful to human health. Thus, many efforts have been focused on exploiting effective EMI shielding materials with low density and strong absorption in a wide frequency range to attenuate those unneeded electromagnetic energies.  The flexible lignin-based magnetic carbon nanofibres developed in Chapter 4 possessed electrical conductivity and magnetic properties comparable to that of PAN-based magnetic carbon nanofibres. PAN-based magnetic carbon nanofibres have been utilized as electromagnetic interference (EMI) shielding materials20,86,126. The same applications have been proposed for lignin based carbon nanofibres. Herein, the application of lignin-based magnetic carbon nanofibres for shielding electromagnetic interference (EMI) was demonstrated, which is the first time to use lignin for EMI shielding application. Shielding effectiveness (SE) of lignin-based magnetic carbon nanofibre (mCNF) was characterized and compared with conventional petroleum-based (PAN-based) carbon nanofibre. 5.2 Materials and Methods 5.2.1 Materials Polydimethylsiloxane (PDMS) was Dow Corning Sylgard 184 Silicone Encapsulant from Ellsworth adhesives.        89  5.2.2 EMI Shielding Test  Lignin-based magnetic carbon nanofibres (mCNFs) for the EMI shielding test were prepared from the solution 3 % IAA - 35% F4   and 10% IAA - 35% F4 , which were thermostabilized at 250˚C with 1˚C/min and then carbonized at 900˚C and 1000˚C The samples are denoted as 3A900,3A1000,10A900 and 10A1000, respectively.  The samples were subsequently coated with polydimethylsiloxane (PDMS) to better withstand the necessary handling for EMI shielding testing. PDMS has low permittivity and permeability and is transparent for electromagnetic waves20, and therefore, any shielding effect of the composites can be attributed totally to the nanofibre contribution.  A coaxial transmission line test fixture was used to measure S parameters from 10 MHz to 18.2 GHz to test broad frequency.161 A rectangular waveguide WR90 were used to measure the S parameters in the Frequency range of 8.2-12.4GHz.20 Thickness of each sample (m-CNF/PDMS) was recorded, respectively. The scattering parameters (S parameters) were measured using Agilent PNA E8362C Network Analyzer. The measurements of the transmittance (T), reflectance (R), and absorbance (A) through the shielding material were made. These were obtained from the following equations using the S parameters: T = S122 = S212, R = S112 = S222, A = 1−R−T.  The effective absorbance (Aeff) was defined as Aefff= (1-R-T)/(1-R) and was obtained with respect to the power of the incident electromagnetic wave. If multiple reflections were negligible, the shielding by reflection (SER) and shielding by absorption (SEA) were defined as SER= -10log10 (1-R) and SEA =-10log10 (T/ (1-R)).          90  5.2.3 Complex Permittivity Test We utilized rectangular waveguide (WR90: Frequency 8.2-12.4GHz) and two 10mm movable polytetrafluoroethylene (PTFE) blocks (PTFE blocks as stable plugs for holding thin solid samples in place so that there will be no sagging of the samples) to measure S parameters (Figure 5-1) 162. The thickness of each sample (m-CNF/PDMS) was recorded, respectively. The measurements were preformed according to the transmission/reflection method using network analyzer in the frequency range from 8 to 12 GHz. The complex permittivity was calculated from S parameters.    Figure 5-1 Schematic of the measurement of complex permittivity162 (VNA denotes the vector network analyzer)  5.3 Results and Discussions 5.3.1 EMI Shielding Test  EMI shielding effectiveness (SE) of a material is defined as the ratio of transmitted power to incident power, and given by SE (dB) =-10 log(PT/P0), where PT  is the transmitted electromagnetic power, and P0  is the incident electromagnetic power.         91  The typical EMI shielding efficiency (SE) results of magnetic lignin carbon nanofibres was tested at working frequencies between 10MHz-18 GHz (as seen in Figure 5-2 a). The average thickness of lignin mCNFs-PDMS composite is about 0.2mm. It should be noted that the lignin mCNFs-PDMS composite have a similar level SE at the low frequency range (about 200 MHz to 3 GHz) as at high frequency range such as 8-12 GHz, as shown in Figure 5-2 b.  At low frequency range (10MHz~3GHz), SE performance was compared between lignin shield and recent research results. Lignin-based shield has a normalized shielding efficiency of ~100 dB/mm, higher than that of the petroleum-based CNF or CNT shield. Furthermore, comparison was conducted at 8~12 GHz using the rectangular waveguide for the comparisons with the published data. The results show that magnetic lignin carbon nanofibres have a normalized shielding efficiency of 120 dB/mm, superior to that of petroleum-based magnetic carbon nanofibres20,163 (Figure 5-4).  For both low frequency and high frequency, lignin shields have very competitive performance.    Figure 5-2 Typical EMI SE results for the magnetic lignin carbon nanofibre/PDMS composites in the frequency range of (a) 10 MHz-18 GHz and (b)  10 MHz -3 GHz          92    Figure 5-3 Comparison of EMI SE (1-3 GHz) between the lignin-based magnetic carbon nanofibres and published data  (at 1GHz)   Figure 5-4 Comparison of EMI SE (8-12 GHz) between the lignin-based magnetic carbon nanofibres and published results         93   5.3.2 Shielding Mechanism Shielding mechanism of magnetic lignin carbon nanofibres was investigated by studying the absorbing effectiveness and reflected effectiveness in X-band (8~12 GHz). Figure 5-5 shows shielding effectiveness total (SET), shielding effectiveness reflection part (SER) and shielding effectiveness absorption part (SEA) of 3A900, 3A100, 10A900 and 10A1000. For all tested samples, SEA is in the range of 12~14 dB, while SER is at the level of 6~8 dB. The contribution of absorption to the total EMI SE is larger than the reflection for the system. This result suggests that absorption is the main mechanism of lignin-based mCNFs as EMI shielding materials.                     94         Figure 5-5 Typical SET, SER and SEA of (a) 3A900, (b) 3A1000, (c) 10A900,  and (d) 10A1000 (250-1-60) in the frequency range (8~12 GHz)    5.3.3 Complex Permittivity To understand the superior EMI shielding performance of lignin-based mCNF, the complex permittivity of the lignin-mCNF/PDMS was measured in the frequency range 8-12 GHz (Figure 5-6).  The results indicated that increasing the mass content of m-CNF (3A900) results in increasing in the real part of the permittivity, ɛ'. Both the real and imaginary parts of the lignin m-CNF were one order of magnitude higher than that of petroleum-based CNF or CNT164,165 (Figure 5-7).  c d b a       95     Figure 5-6 (a) Real part and (b) imagery part of complex permittivity for samples (3% IAA, carbonization temperature 900˚C) with different carbon fibre content (4.4 wt. % and 7.5wt. %)  The possible reasons for the superior performance of the lignin-based m-CNF are the porous structure of lignin carbon nanofibres and the large interfacial polarization generated by the uniform presence of the nanoparticles. This explanation is consistent with recent findings which showed the enhancement of microwave absorption due to the porous structure of carbon nanofibres.166,167 Second reason may be the core-shell structure of the nanoparticles, which was seen in section 4.4.1. The effect of a core-shell structure has previously been observed where integrating various dielectric oxide shells and/or magnetic metal cores into one particle enhanced microwave absorption from hierarchical nanostructures, even with complicated morphologies168–171. According to dissipation mechanisms, microwave absorption materials can be categorized into two types: dielectric loss and magnetic loss. The permittivity of a material is related to a variety of physical phenomena. Ionic conduction, dipolar relaxation, atomic polarization, and electronic polarization are the main mechanisms that contribute to the permittivity of a dielectric a b       96  material. In the microwave range, the variation of permittivity is mainly caused by dipolar relaxation.172 When the electromagnetic radiation is incident on the surfaces of lignin-based mCNF, the electric field induces two different electrical currents within material, i.e., the conduction and displacement currents, respectively; the former arises from free electrons (or metallic states) and will give rise to electric loss (imaginary permittivity). The latter comes from the bound charges, i.e., polarization (real permittivity), which mainly involves the unpaired point defects.163 It is believed the high value of permittivity and SE could be attributed to the presence of the porous structure of lignin carbon nanofibres and the large interfacial polarization generated by the core-shell nanoparticles.   Figure 5-7 Complex permittivity results comparison between experimental results and published data          97  5.4 Conclusions EMI shielding potential of lignin based magnetic carbon nanofibres were successfully demonstrated. Shielding effectiveness of lignin magnetic carbon nanofibre mats was comparable to that of PAN-based nanofibre mats. EMI shielding performance was correlated with high complex permittivity and could be modified based on magnetic carbon fibre fabrication conditions such as carbonization temperature and IAA concentration. Lignin-based magnetic nanofibre is a promising low-cost alternative to PAN based fibre for materials requiring high EMI shielding. This research provides insights for designing lightweight and effective microwave absorbers from renewable, sustainably-sourced lignin.  This study also improves our fundamental understanding of the mechanism behind that both SE and complex permittivity are correlated to the fundamental structures of the magnetic carbon nanofibres. Both porous structures of carbon nanofibres and uniform presence of magnetic core-shell nanoparticles might help improve the dielectric performance of composite carbon nanofibres.         98  Chapter 6 : Lignin Carbon Nanofibre for Flexible Lithium Ion Battery Application  6.1 Introduction  The flexible lignin-based carbon nanofibres with transition metal oxide (Fe3O4) described in Chapter 4 had electrical conductivity and the nanoparticles synthesised within the fibres can interact with lithium ions. Previous research shows that transition metal oxides, as anode materials for lithium ion batteries, have gained significant attention due to their higher theoretical capacities than graphite by the formation of metal substance through a chemical conversion mechanism 87,173–182. Among transition metal oxides materials, Fe2O3 and Fe3O4 is believed to be a promising candidate to replace graphite because of its high theoretical capacity (1007 mAhg−1), low cost, ease of fabrication and environmental benignity173. The reactions of these compounds with Li+   can be described as follows: MOx + 2xLi+ + 2xe- ↔ xLi2O + M For example, iron oxide can interact with Li+ as illustrated below: 6Li+ + Fe2O3 + 6e- ↔ 2Fe + 3 Li2O 8Li+ + Fe3O4 + 8e-↔ 3Fe + 4Li2O The experimental values of potential for the plateaus associated with conversion reactions in Fe2O3 and Fe3O4  is 0.8 V 183. Moreover, with the advancement of the modern technology, future demand necessitates the development of advanced flexible lithium ion batteries. However, designing flexible LIB is facing many challenges in a rational assembly of flexible electrolytes/separators, flexible electrode materials, flexible current collectors and flexible packaging. Flexible electrode       99  materials are core components for constructing flexible LIBs. Until now, the main electrode materials for flexible LIBs are membrane/paper-like carbon-based materials from CNTs, graphene and carbon cloth/textiles184,185. Different electrode materials have their own advantages and shortcomings. Electrodes of graphene, CNT and carbon cloth/fabric electrodes have good electrical conductivity and flexibility, while their low reversible capacity, low Coulombic efficiency and non-ideal insertion/extraction voltage profiles are fatal weaknesses for possible practical applications184,185. For other low-dimension nanostructured materials, except for CNTs and graphene materials, flexibility and mechanical strength are not a problem; however, cost and electrical conductivity are two limiting factors. Yet, these above materials are non-renewable, and will gradually become more costly and whose negative environmental impacts are clear. Paper (cellulose) and fabrics have low cost and excellent flexibility, but their electrical conductivity is very limited or they can even be insulating.186  Thus, the continuing search for renewable flexible electrode materials is quite necessary.  Among the flexible electrolytes, gummy electrolyte (GE) is one of the most promising solid polymer electrolyte 187. Solid polymer electrolyte has been studied to replace liquid electrolyte in the lithium ion battery to solve the safety problem of lithium ion battery. However, the issue of using solid electrolyte is the large interfacial resistance between the traditional electrode and electrolyte. Gummy electrolyte has relevantly high flexibility, fairly high ionic conductivity and good adhesive properties187.   In this chapter, we tested the use of flexible lignin-based carbon nanofibres as anode material for flexible LIB. We investigated the interfacial compatibility between the lignin       100  electrodes and the gummy electrolyte. We first fabricated and characterized a flexible LIB anode, then integrated it with gummy electrolyte, and assembled and tested the whole battery.  6.2 Materials and Methods 6.2.1 Materials 1M LiPF6 (in a 1:1 v/v ethylene carbonate: dimethyl carbonate in 2% vinylene carbonate) solution is purchased from SOLVIONIC SA. Three of LIB electrodes were prepared from lignin carbon nanofibres, namely a non-interconnected electrode (CNF from F4 thermalstablized at 5 ˚C/min, and carbonized at1000˚C), a 3-D interconnected electrode (7:3 F4:F1-3, thermalstablized at 1C/min, and carbonized at 1000˚C), and a flexible electrode (3%IAA, thermalstablized at 1C/min, and carbonized at 1000˚C). 6.2.2 Methods A three electrode cell was assembled in the glove box with argon atmosphere using Li metal as both the reference electrode (RE) and counter electrode (CE).  Lignin-based CNF mats were used as the working electrode (WE).  The assembly was tightly sealed, and was immersed in a LiPF6 electrolyte solution. The cell was cycled between 1.2 and 0.05 V at 22 mA/g rate using an AMEL Model 7050 potentiostat to evaluate the charge/discharge cycling behavior of lignin-based CNF anode. Contact angle measurement was conducted using gummy electrolyte solution (prepared according to the literature187) as the liquid phase, and the CNF as the substrate.  The flexible battery was fabricated as follows: a flexible lignin-based carbon electrode was placed on copper tape; gummy electrolyte solution (prepared according to the literature187)       101  was coated on the electrode, dried in air for 24 hours, then dried in a vacuum oven at 80˚C for 48 hours. The Li metal was flattened against the electrolyte-coated electrode in the glove box under argon. A schematic of the assembled flexible battery is shown in Figure 6-1.  Figure 6-1 Schematic of the fabrication process of the flexible battery 6.3 Results and Discussions 6.3.1 Fabrication of Flexible LIB Anode from Lignin The first step was characterizing the electrochemical property of the flexible lignin carbon nanofibres anode. Charge and discharge cycling tests show the capacity of the flexible lignin based anode is comparable to that of a commercial graphite anode. Three of LIB electrodes were prepared from lignin carbon nanofibres, namely a non-interconnected electrode, a 3-D interconnected electrode and a flexible electrode (Figure 6-2).        102     non-flexible non-flexible flexible Figure 6-2 SEM images of three types of LIB electrodes from lignin carbon nanofibres as (a) non-interconnected electrode (CNF from F4 thermalstablized at 5 ˚C/min, and carbonized at1000˚C), (b) 3-D interconnected electrode (7:3 F4:F1-3 , thermalstablized at 1C/min, and carbonized at1000˚C), and (c) flexible electrode (3%IAA, thermalstablized at 1C/min, and carbonized at1000˚C)   The charge/discharge test results of these three types electrodes (at a current density of 30 mA/g) are shown in Figure 6-3 (a, b and c). All lignin carbon nanofibre electrodes were found to be electrochemically stable in the voltage window between 50 mV and 3 V versus Li/Li+ in LiPF6 solution. The capacity of non-interconnected electrode was 200~250 mAh/g, whereas the capacity of 3-D interconnected electrode was 100~150 mAh/g. The flexible electrode was doped with 3% IAA (Figure 6-2,c).The capacity of the flexible electrode was 350~400 mAh/g, which was comparable to the commercial graphite anode (370 mAh/g).  a c b       103      Figure 6-3 The charge/discharge curves of carbon nanofibre electrode from lignin (black line: 1st cycle, red line: 2nd cycle, and blue line: 3rd cycle): (a) non-interconnected,(b) 3-D interconnected, and (c) flexible electrode.   6.3.2 Integration of the Flexible Lignin Anode and Gummy Electrolyte The second step was to integrate the flexible lignin anode with the gummy electrolyte (GE).  The GE had an ionic conductivity of ~ 10-3 S/cm. The morphology of the flexible lignin electrode integrated with the gummy electrolyte can be seen in the cross-section image shown in Figure 6-4. The compatibility between the flexible lignin electrode and the GE were characterized based on the contact angle (Figure 6-5). For the commercial graphite anode, the a b c       104  contact angle was decreasing from ~90˚ to ~40˚ in 5 minutes, whereas for the flexible electrode, the contact angle was changing from ~60˚ to 10˚ in 1.5 min minutes.  The results showed an improved compatibility between the GE and the flexible lignin anode compared to the commercial graphite anode.  The possible reason is that nanofibres have the advantage of large surface area, compared with graphite particles. Therefore, nanofibres improve the wettability between the electrode and electrolyte.   Figure 6-4 SEM image of the cross-section of the flexible lignin electrode integrated with the gummy electrolyte   a b       105   Figure 6-5  Contact angle measurement (a) gummy electrolyte on commercial graphite anode and (b) gummy electrolyte on flexible lignin carbon nanofibre electrode; (c) dynamic changes of the contact angles   6.3.3 Flexile Battery Assembly and Testing Finally, we assembled a solid state battery with a lignin-based anode using GE to characterize the battery performance. A galvanostatic charge/discharge (GCD) test was done to show the battery was able to be charged and discharged. The initial charge capacity was ~100 mAh/g and discharge capacity was a few mAh/g, and decreased to about zero after 4 cycles.  The capacity of the flexible battery from lignin electrodes was compared with the published results. Ajayan et al. fabricated porous cellulose paper embedded with aligned CNTs composite paper electrode.188 This composite paper exhibited superior flexibility and could be rolled up, twisted, even bent to any degree and was completely recoverable, which could be directly used as the flexible electrode for paper battery.188 It was reported that the assembled flexible paper battery exhibited a reversible capacity of 110 mAh/g and could be repeated over several tens of cycles of charging and discharging.188  Therefore, although achievements regarding flexible batteries from c       106  lignin have been obtained by as mentioned above, drawbacks still exist and need to be conquered to improve the performance of the fabricated flexible LIBs from lignin. The following research aspects should be considered in the future. The penetration of the gel electrolyte within the lignin nanofibrous electrode may not have been perfect and has to be improved. The interfacial resistance has to be reduced to future improve the battery performance.  Figure 6-6 Battery charge and discharge cycling test  6.4 Conclusions We demonstrated the feasibility of using lignin based CNF as the lithium ion battery anode. Particularly, the capacity of the flexible lignin based anode is comparable to that of the commercial graphite anode.  Flexible solid state lithium ion batteries have been prepared from this flexible lignin CNF anode and gummy electrolyte. The results show that via using CNF as the electrode, the wettability between the electrode and electrolyte was improved. But the performance of the flexible battery from lignin has to be improved in the future work.         107  Chapter 7 : Lignin-based, Moisture-driven Actuator  7.1 Introduction In the process of developing multifunctional lignin carbon nanofibres, we observed a unique actuating phenomenon in thermostabilized lignin nanofibres. This phenomenon can be attributed to the differential swelling of the nanofibre assemblies upon exposure to moisture analogous to the opening and closing of the stomata in a leaf. In order to develop potential applications of this phenomenon, a detailed analysis of the mechanism was carried out to assess the lignin-based, moisture-driven actuator. 7.2 Materials and Methods The lignin based moisture driven actuator was fabricated in section 4.4.2 with F4:F1-3 with different ratios and thermostabilized with a heating rate of 5 ˚C/min up to 250˚C and held for 1 hour. Its movement was characterized using a camera set up with 1/32 seconds for one frame. Fourier transform infrared spectrometer (FT-IR) (Perkin-Elmer 16 PC FT-IR spectrometer) was used to analyze the chemical structure of as-spun, thermostabilized and carbonized fibres. The spectrum was measured with an average of 8 scans and a resolution of 4 cm-1 over the range of 500 to 4000 cm−1. 7.3 Results and Discussions 7.3.1 Actuating Phenomenon The lignin actuator exhibits fast, reversible and dramatic mechanical deformation and recovery in response to environmental moisture. Three basic actuation responses – contraction, expansion, and rotation – can be combined together within a single type material of lignin (Figure 7-1). All the motion response time is less than 30 milliseconds.  This phenomenon will       108  bring in wide advanced applications of lignin actuator. For example, the potential energy of a moisture gradient can be converted inside the lignin actuator and stored as elastic potential energy, and then might be used to produce mechanical work or to create electricity in the future. In the previous publication, actuator was prepared from polypyrole (PPy) using chemistry synthesis. The price for pyrrole is $3000 ~3500 per ton.189 The commercial price of lignin is $400~500 per ton.190 The lignin actuator from lignin was processed by simple electrospinning and thermostablization. Therefore, lignin is a low-cost precursor for the actuator and the preparation method of lignin-based actuator was fairly easier than that of the PPy-based actuator.       t=0 t=1/32s    t=0 t=20/32s t=40/32s Figure 7-1 High speed camera photo of the fast actuation responses of lignin actuator on moisture substrate: (a-b) contraction and expansion motion and (c-e) rotation motion e d c a b       109   The mechanism of motion for the lignin actuator is as illustrated in Figure 7-2. One locomotive cycle of a lignin film was typically composed of five stages (1 to 5) similar to a PEE-PPy actuator142. As the actuator contacted the moist substrate, the bottom face expanded more than the top face, causing asymmetric the bending away from the substrate (2). The contact surface area decreased and the film’s center of gravity rose and became unbalanced. The film eventually went through buckling and toppling (3). Next, the actuator rolled up (4) or the film fell back to the substrate with the other side down (5) to start another cycle.        110   Figure 7-2 Locomotion of a lignin actuator film on a moist substrate (1): asymmetric swelling the curling away from the substrate (2); the contact surface area decreased and the film’s center of gravity rose, leading to mechanical instability (2); the buckling and toppling of the film (3); the actuator rolled up into a carpet (4);  the film fell back to the substrate with a new face down (5) to start a new cycle.  The thickness of the actuator is a critical parameter which determines how fast the actuator performs locomotion. Regarding to the required thickness of the actuator to perform fast locomotion, equations from a theoretical thermodynamic analysis of the water-induced expansion/contraction cycle can roughly define a theoretical maximum and minimum limit. Ma et. al. have demonstrated the theory to estimate the maximum and minimum limit on the required       111  thickness of the actuator to perform fast locomotion.142  In principle, the  overall  Gibbs  free  energy  change  of  absorbed  water  during  one  expansion-contraction cycle is  ∆𝐺 𝑐𝑦𝑐𝑙𝑒 = ∆𝐺 𝑠𝑜𝑝𝑟𝑡𝑖𝑜𝑛 + ∆𝐺 𝑟𝑒𝑙𝑒𝑎𝑠𝑒 < 0.  The lignin film has dimensions of length (l), width (w) and thickness (d) , which absorbs water to buckle up with a curvature R and a radian θ, where l = R×θ . Assume that change in the film’s thickness during water sorption is negligible and that the film’s volume expansion upon water sorption equals to the absorbed water volume. The volume expansion can be calculated as 142 𝑉𝑜𝑙𝑢𝑚𝑒 𝑒𝑥𝑝𝑎𝑛𝑠𝑖𝑜𝑛 =  𝜃 (𝑅+𝑑)2 𝑤−𝜃𝑅2𝑤2− 𝜃𝑅𝑑𝑤 =𝜃𝑑2𝑤2  . Since the overall Gibbs free energy change of absorbed water should be higher than the maximum elastic potential energy stored in one cycle,  Given l = R×θ , the reduced final equation is  142.  On  the  other  hand,  the  actuator  should  be  able  to  use  the  maximum  elastic  potential energy stored in one cycle to overcome the attractive interaction with the moist substrate  and the gravity to buckle up, we get. .142  The reduced final equation is  where E is the elastic modulus of the actuator, ρ and M are the density and molecular weight of water respectively, and fad  is the adhesive coefficient between lignin actuator and the moist substrate.142          112  7.3.2 Investigation of Movement Mechanism 7.3.2.1 Fibre Interconnection  To control the actuation response, both the physical structure and chemical structure had to be adjusted simultaneously. To obtain fibres capable of actuation, lignin fibres have to be fused at a particular degree (the ‘fusing degree’) otherwise fibre spacing will buffer the shape change. We experimented with the fusing degree by increasing the amount of F1-3 in the thermostabilized nanofibre blend. As a result, with increasing amounts of F1-3, the fusing degree, or interconnection of fibres, increased (Figure 7-3). Thermostabilized fibres spun from F4 and 7:3 F4:F1-3 didn’t show actuation, but 6:4 F4:F1-3 and 5:5 F4:F1-3 did show an actuation response to moisture.  The degree of fibre interconnection is a key parameter for an actuating response. For (a) and (b) in Figure 7-2, the degree of interconnection is low and force cannot be transported and no actuation occurs. For (c) and (d), the connections are numerous enough that force can be transported between fibres and the samples show a responsive to the water vapor.       113    Figure 7-3 Correlation between fibre morphology and response (a, b) non-responsive to water, and (c,d) responsive to water vapor (scale bar 10 um) 7.3.2.2 Presence of Two Phase Structures The presence of two phase structures is also necessary for a strong actuation. During thermal oxidation, the F1-3 and F4 blend cross-linked with themselves and formed an interpenetrating network when exposed to the proper heating rate (5˚C/min). Dynamic rheology results have shown two Tg were present in actuated lignin film while one Tg was present in non-actuated lignin film51.  The phase with lower Tg is soft phase, and the one with higher Tg is the rigid phase. It is speculated that interpenetrating polymer network was formed within the lignin actuator.       114  7.3.2.3 Tendency to Form Hydrogen Bond  A strong actuation response in lignin depends on having carbonyl functional and hydroxyl group should be present. Thermostabilized fibres from 5:5 F4:F1-3 were carbonized at different temperatures: 400˚C, 500 ˚C and 600 ˚C. The results were the higher the temperature, the slower the actuation response. At 600 ˚C, the response disappeared. SEM images confirmed that the sample morphology did not change (Figure 4-31). However, the number of carbonyl and hydroxyl groups decreased as seen in Figure 7-4, demonstrating the importance of having functional group to form hydrogen bonding in propagating the actuation force.  Further, the intensity of C=O and hydroxyl group decreased in the carbonization process (Figure 7-4) with the increase the carbonization temperature, which indicating the loss of the organic functional group in the carbonization process.  Figure 7-4 FT-IR spectra of thermostabilized fibres from F4: F1-3 (5:5) and the carbonized nanofibres at 400, 500 and 600˚C  1710 cm-1 1590 cm-1 -OH group       115  7.3.2.4 Interaction with Water Vapor The mechanism of moisture-gradient driven actuator for lignin has been attributed to disruption of hydrogen bonds by water adsorption and penetration. The fibre network is sensitive to water vapor by the processes of adsorption, diffusion and solvation. These processes impact the intermolecular hydrogen bonding between the lignin molecules, whose size and properties differ between the F1-3 and F4 networks. The adsorption, diffusion and solvation alter the shape of the lignin actuator.  The water vapor molecules adsorb and diffuse through the lignin actuator to reach their final sites. Because the phase of F1-3 is “softer” than F4, water molecules readily access the F1-3 network, resulting in greater expansion relative to the rigid phase of F4, as illustrated in Figure 7-5. At the same time, the interconnected structure of the lignin actuator forms larges pores for the water, providing the easier pathway of the water molecules through the lignin actuator. For our porous lignin actuator with submicron scale interconnected pore channels, the water vapour molecules can directly travel to the pore surfaces via the unhindered (percolating) micron-sized pore channel access.       116    Figure 7-5 Actuation mechanism of lignin actuator  Solvation is the process of attraction and association of molecules of a solvent with molecules or ions of a solute.191 The concept of the solvation interaction can also be applied to an insoluble material, for example, solvation of functional groups on a surface of ion-exchange resin.191 Polar solvents are those with a molecular structure that contains dipoles. Such compounds are often found to have a high dielectric constant. The polar molecules of these solvents can solvate ions because they can orient the appropriate partially-charged portion of the molecule towards the ion in response to electrostatic attraction. This stabilizes the system and creates a solvation shell (or hydration shell in the case of water). 191 Water is the most common and well-studied polar solvent. In this case of the lignin, the solvation process enlarged spaces       117  between lignin molecules and caused the expansion of actuator. After the complete evaporation of the water molecules, the material recovers to the dry state of the actuator.  For the lignin nanofibres tested here, the process of solvation was fast at milliseconds level.  For disordered media, the solvation process is usually expressed via the solvation time correlation function: 𝐶 (𝑡) =E(t)−E(∞) E(0) −E(∞), where E(0) and E(∞) are the energy of the system at the beginning and at the end of the dynamics (i.e. corresponding to initial polarization P(0) and final polarization P(∞)), while E(t) is the energy at some intermediate time during the dynamics. The correlation function typically exhibits a multi exponential decay with time scales of <200 fs, some 100s of fsec and a few psec to several tens of psec, depending on the solvent, which are due to bulk polarization, damped rotations and diffusive rotation and translation, respectively.192  Intermolecular hydrogen bonding also modulates intermolecular packing to alter its mechanical properties in response to water. In summary, the solvation process attributes to the robust response of lignin based actuator. Lignin-based actuators displayed fast mechanical movement at millisecond level, whereas most other polymer actuators exhibit relatively slow and small-scale movements. Furthermore, the lignin actuator is prepared from low-cost renewable resources with a simple process, compared to others which are easily damaged and involve complex materials and preparation.  7.4 Conclusion The lignin nanofibre actuator, prepared by electrospinning and thermostabilization, exhibited fast, reversible and dramatic mechanical deformation and recovery in response to       118  moisture gradients. The actuation mechanism was investigated at the molecular level and fibre level and three key factors were found: two phase structures, the functional groups such as hydroxyl and carbonyl groups for hydrogen bonding, and a sufficient degree of interconnection between fibres. It is expected that the inexpensive and effective lignin-based actuator can be used in the development of ultrasensitive sensors, energy harvesting, and microclimate controlled clothing in the future.         119  Chapter 8 : Conclusions and Future Directions 8.1 Conclusions This study has explored the feasibility of creating multifunctional lignin materials in nanofibre form in order to develop a material platform for the development of value-added products from lignin. We demonstrated that multifunctional lignin nanofibres can be successfully fabricated by electrospinning, thermostabilization and carbonization. Subsequently, various key functions were introduced to lignin-based nanofibres and the structures and properties of multifunctional lignin nanofibres were characterized. Furthermore, these functions enabled development of advanced applications, including EMI shielding, lithium-ion battery and actuator. The findings of this research project can be summarized as follows: We have developed multifunctional lignin nanofibres using the technique of electrospinning, thermostabilization and carbonization. We successfully incorporated chemical, electrical, magnetic, electrochemical functions and bending flexibility into lignin nanofibres. These functionalities were successfully introduced at three levels, including (i) the molecular level; (ii) the fibre level; (iii) the fibre assembly level. Specifically, at the molecular level, chemical functionalities were added due to the formation of a large amount of carbonyl carboxylic groups and hydroxyl groups by thermal oxidative treatment of lignin nanofibres. We found that these functional groups turned hydrophobic lignin nanofibres into a hydrophilic material. The presence of these functional groups also facilitates the ability of the 3-D interconnected thermostabilized nanofibre mats to interact with water.  These lignin nanofibres with functional groups represent a new material       120  platform. We anticipate it will expand the functionalization and applications of lignin making use of the functional groups. At the fibre level, electrical functions, magnetic functions and bending flexibility were introduced to lignin nanofibres. Lignin-based composite carbon nanofibres embedded with in-situ synthesized nanoparticles from IAA were successfully prepared via electrospinning, thermostabilization and carbonization. As a result of in-situ nanoparticles synthesis, the structure of porous carbon nanofibre with core-shell nanoparticles was observed for composite carbon nanofibres. By simply tuning the heating rate of thermostabilization and IAA concentration, the nanoparticles composition and crystal structure are able to be manipulated. The electrical conductivity of electrospun composite carbon nanofibres was comparable to that of PAN-based electrospun carbon nanofibres. Magnetic properties of lignin-based electrospun composite carbon nanofibres were also comparable to that of PAN-based electrospun carbon nanofibres. The amorphous structure of lignin and the addition of functional fillers impart bending flexibility to lignin carbon nanofibre mats. The resultant lignin-based composite carbon nanofibres are flexible, electrical conductive and magnetic active, indicating their applicability in electromagnetic related areas.  At the fibre assembly level, nanofibres were designed to be interconnected in 3-D. Our results showed that the electrical conductivity of the architecture-designed carbon nanofibres was ~ 50 S/cm. In comparison, the electrical conductivity of non-interconnected lignin-based carbon nanofibres was at the level of 5 S/cm. Therefore, the designed architecture improves the electrical conductivity by one order of magnitude.  Electrical conductivity is very important for       121  electrical applications. It is expected it may be used in electronic components, devices and their related areas. We used three examples to illustrate the advanced applications of the above functionalized lignin-based carbon nanofibres, including (i) electromagnetic interference shielding, (ii) lithium-ion battery, and (iii) actuator.  We designed flexible EMI shields using fibre level functionalized lignin nanofibres (composite carbon nanofibres) demonstrated better shielding effectiveness to that of PAN-based nanofibres. This study improves our fundamental understanding of the mechanism behind the observation that superior shielding performance and complex permittivity are correlated with fundamental structures of magnetic carbon nanofibres. Both the porous structures of carbon nanofibres and the uniform presence of magnetic core-shell nanoparticles help to improve the dielectric performance of composite carbon nanofibres.  In addition, using the fibre level functionalized lignin nanofibres (composite carbon nanofibres), we created free-standing and binder-free flexible lithium ion battery anodes for flexible lithium-ion batteries. The capacity of flexible lignin based anode was comparable to that of commercial graphite anode and, could be successfully assembled into flexible lithium-ion batteries using a ‘gummy’ electrolyte. The lignin carbon nanofibres with large surface area could interact with the solid electrolytes. Accordingly, the compatibility between lignin-based nanofibre anode and solid electrolytes was better than that of commercial graphite anode and solid electrolytes.  Moreover, a moisture-driven actuator prepared using the molecular level and fibre assembly level functionalized lignin nanofibres, exhibited robust, reversible and dramatic       122  mechanical deformation and recovery in response to moisture gradients. The actuation mechanism was investigated at the molecular level and fibre level and three key factors were found: a) two phase structures, b) the existence of functional groups such as hydroxyl and carbonyl groups for hydrogen bonding, c) a sufficient degree of interconnection between fibres and d) the solvation effect.  In conclusion, we presented 3 examples of functionalization of lignin nanofibres at 3 different levels, using the technique of electrospinning and subsequent heat treatment. In addition, we demonstrated 3 examples of advanced applications for multifunctional lignin nanofibres. We showed that the nanofibre form of lignin is an effective material platform to add key functionalities to lignin. Moreover, functionalizing lignin nanofibres represents a robust and versatile value-adding option for lignin. The encouraging findings summarized here contribute a promising pathway for lignin to serve as a renewable engineering material.  8.2 Future Directions Specific recommendations for the direction of future research on multifunctional lignin are provided here, based on three levels of functionalization and three applications of multifunctional nanofibres.  For the functionalization of lignin nanofibres on the molecular level, nanofibres from lignin possess various functional groups available for functionalization and modification. This study directly used the chemical functions from the functional groups. However, there are plenty of opportunities to carry out surface modifications for functional groups on electrospun lignin nanofibres and thermostabilized nanofibres to design new materials with novel functionality. For functionalization of lignin nanofibres on the fibre level, various functional nanoparticles could be       123  introduced into lignin nanofibres to to meet different applications requirements. For the functionalization of lignin nanofibres on the fibre assembly level, differing architectures (random, aligned or interconnected) could be designed to achieve the corresponding intended functionalities and applications.   For the applications of lignin-based multifunctional nanofibres, we tested the flexible composites for EMI shielding, and demonstrated comparable efficiency to PAN-based carbon nanofibres. In the future, further optimization of shielding performance will be required. It is also important to investigate the techniques for mounting this type shielding materials and to further identify and test the real applications, including the specific case of gaskets.  Another example that we demonstrated is development of flexible lithium-ion batteries using lignin-based carbon nanofibres as the anode. The energy density delivered by flexible batteries was limited by battery assembly techniques and the performance of the electrodes and electrolytes. In this study, we prepared the architecture-designed lignin-based composite carbon nanofibres. It is hypothesized this novel material could simultaneously generate flexibility, high capacity and better rate performance. It is recommended to assemble, test and optimize architecture-designed lignin-based composite carbon nanofibres as the electrode with solid electrolyte to improve the performance of the flexible battery.  We investigated the mechanism of the moisture-triggered actuator but it needs to be fully characterized, including the measurement of contractile force and stress, and the characterization of response energy and response time. The inexpensive and effective lignin-based actuator is expected to be of use in the development of ultrasensitive sensors, energy harvesting, and microclimate controlled clothing in the future.         124  In the future, the integrated design for scale up manufacturing of the various functionalized lignin nanofibres and its products should be established.              125  References 1. Our Vision of Lignin-based Materials and Chemicals. at <http://www.lignoworks.ca/content/vision-and-purpose > date acessed : July 2015 2. Benoit, L. Canada’s forest industry: recognizing the challenges and opportunities. (2008). 3. Ragauskas, A. J. et al. Lignin valorization: improving lignin processing in the biorefinery. Science 344, 1246843 (2014). 4. Kleinert, M. & Barth, T. Phenols from Lignin. Chem. Eng. Technol. 31, 736–745 (2008). 5. Baker, D. A. & Rials, T. G. Recent advances in low-cost carbon fiber manufacture from lignin. J. Appl. Polym. Sci. 130, 713–728 (2013). 6. Ruiz-Rosas, R. et al. The production of submicron diameter carbon fibers by the electrospinning of lignin. Carbon N. Y. 48, 696–705 (2010). 7. Baker, D. A., Gallego, N. C. & Baker, F. S. On the characterization and spinning of an organic-purified lignin toward the manufacture of low-cost carbon fiber. J. Appl. Polym. Sci. 124, 227–234 (2012). 8. Kadla, J. . et al. Lignin-based carbon fibers for composite fiber applications. Carbon N. Y. 40, 2913–2920 (2002).       126  9. Kubo, S. & Kadla, J. F. Lignin-based Carbon Fibers: Effect of Synthetic Polymer Blending on Fiber Properties. J. Polym. Environ. 13, 97–105 (2005). 10. Lora, J. H. & Glasser, W. G. Recent Industrial Applications of Lignin: A Sustainable Alternative to Nonrenewable Materials. J. Polym. Environ. 10, 39–48 (2002). 11. Gosselink, R. J. A., de Jong, E., Guran, B. & Abächerli, A. Co-ordination network for lignin—standardisation, production and applications adapted to market requirements (EUROLIGNIN). Ind. Crops Prod. 20, 121–129 (2004). 12. Saito, T. et al. Turning renewable resources into value-added polymer: development of lignin-based thermoplastic. Green Chem. 14, 3295–3303 (2012). 13. Jeong, H., Park, J., Kim, S., Lee, J. & Ahn, N. Compressive Viscoelastic Properties of Softwood Kraft Lignin-based Flexible Polyurethane Foams. 14, 1301–1310 (2013). 14. Ko, F. K. & Wan, Y. Introduction to Nanofiber Materials. (Cambridge University Press, 2014). 15. Morgan, P. Carbon Fibers and Their Composites. (Taylor & Francis, 2005). 16. Braun, J. L., Holtman, K. M. & Kadla, J. F. Lignin-based carbon fibers: Oxidative thermostabilization of kraft lignin. Carbon N. Y. 43, 385–394 (2005).       127  17. Tao, X. Y. et al. Synthesis of multi-branched porous carbon nanofibers and their application in electrochemical double-layer capacitors. Carbon N. Y. 44, 1425–1428 (2006). 18. Suresh Kumar, P. et al. Free-standing electrospun carbon nanofibres—a high performance anode material for lithium-ion batteries. J. Phys. D. Appl. Phys. 45, 265302 (2012). 19. Bayat, M., Yang, H. & Ko, F. Electromagnetic properties of electrospun Fe3O4/carbon composite nanofibers. Polymer (Guildf). 52, 1645–1653 (2011). 20. Bayat, M., Yang, H., Ko, F. K., Michelson, D. & Mei, A. Electromagnetic interference shielding effectiveness of hybrid multifunctional Fe3O4/carbon nanofiber composite. Polymer (Guildf). 55, 936–943 (2014). 21. Hu, T. Q. Chemical Modification, Properties and Usage of Lignin. (Kluwer Academic/Plenum Publishers, 2002). 22. Boerjan, W., Ralph, J. & Baucher, M. Lignin Biosynthesis. Annu. Rev. Plant Biol. 54, 519–546 (2003). 23. Glasser, W. G., Northey, R. A. & Tor P. Schultz. Lignin: Historical, Biological, and Materials Perspectives. ACS Symp. Ser. 742, (American Chemical Society, 1999). 24. Calvo-Flores, F. G. & Dobado, J. A. Lignin as renewable raw material. ChemSusChem 3, 1227–35 (2010).       128  25. Josef Gierer. Lignin: Historical, Biological, and Materials Perspectives. 742, (American Chemical Society, 1999). 26. Carbon Fiber Industry Future | Market Size Report. (2012). at <http://www.smithersapex.com/products/market-reports/carbon-fiber-future-industry-market-size-report> date accessed: July 7 2015 27. Frank, E., Hermanutz, F. & Buchmeiser, M. R. Carbon Fibers: Precursors, Manufacturing, and Properties. Macromol. Mater. Eng. 297, 493–501 (2012). 28. Pandolfo, A. G. & Hollenkamp, A. F. Carbon properties and their role in supercapacitors. J. Power Sources 157, 11–27 (2006). 29. Yu, G., Xie, X., Pan, L., Bao, Z. & Cui, Y. Hybrid nanostructured materials for high-performance electrochemical capacitors. Nano Energy 2, 213–234 (2013). 30. Al-Saleh, M. H. & Sundararaj, U. Electrically conductive carbon nanofiber/polyethylene composite: effect of melt mixing conditions. Polym. Adv. Technol. 22, 246–253 (2011). 31. ASM Handbook, Volume 21. (ASM International, 2001). 32. Yardim, M., Ekinci, E. & Bartle, K. in Des. Control Struct. Adv. Carbon Mater. Enhanc. Perform. 125–134 (2001).       129  33. Liu, J., Wang, P. H. & Li, R. Y. Continuous carbonization of polyacrylonitrile-based oxidized fibers: Aspects on mechanical properties and morphological structure. J. Appl. Polym. Sci. 52, 945–950 (1994). 34. Bashir, Z. A critical review of the stabilisation of polyacrylonitrile. Carbon N. Y. 29, 1081–1090 (1991). 35. Rahaman, M. S. A., Ismail, A. F. & Mustafa, A. A review of heat treatment on polyacrylonitrile fiber. Polym. Degrad. Stab. 92, 1421–1432 (2007). 36. S. Otani, Y. Fukuoka, B. I. and K. S. Method for producing carbonized lignin fiber. (1969). 37. Sudo, K., Shimizu, K., Nakashima, N. & Yokoyama, A. A new modification method of exploded lignin for the preparation of a carbon fiber precursor. J. Appl. Polym. Sci. 48, 1485–1491 (1993). 38. Sudo, K. & Shimizu, K. A new carbon fiber from lignin. J. Appl. Polym. Sci. 44, 127–134 (1992). 39. Eckert, R. C. & Abdullah, Z. Carbon fibers from kraft softwood lignin. (2010). 40. Huang, Z.-M., Zhang, Y.-Z., Kotaki, M. & Ramakrishna, S. A review on polymer nanofibers by electrospinning and their applications in nanocomposites. Compos. Sci. Technol. 63, 2223–2253 (2003).       130  41. Persano, L., Camposeo, A., Tekmen, C. & Pisignano, D. Industrial Upscaling of Electrospinning and Applications of Polymer Nanofibers: A Review. Macromol. Mater. Eng. 298, 504–520 (2013). 42. Schiffman, J. D. & Schauer, C. L. A Review: Electrospinning of Biopolymer Nanofibers and their Applications. Polym. Rev. 48, 317–352 (2008). 43. Zhang, C.-L. & Yu, S.-H. Nanoparticles meet electrospinning: recent advances and future prospects. Chem. Soc. Rev. 43, 4423–48 (2014). 44. Zhang, L., Aboagye, A., Kelkar, A., Lai, C. & Fong, H. A review: carbon nanofibers from electrospun polyacrylonitrile and their applications. J. Mater. Sci. 49, 463–480 (2013). 45. Lallave, M. et al. Filled and Hollow Carbon Nanofibers by Coaxial Electrospinning of Alcell Lignin without Binder Polymers. Adv. Mater. 19, 4292–4296 (2007). 46. Dallmeyer, I., Ko, F. & Kadla, J. F. Electrospinning of Technical Lignins for the Production of Fibrous Networks. J. Wood Chem. Technol. 30, 315–329 (2010). 47. Dodd, A. P., Kadla, J. F. & Straus, S. K. Characterization of Fractions Obtained from Two Industrial Softwood Kraft Lignins. ACS Sustain. Chem. Eng. 3, 103–110 (2014). 48. Cui, C., Sun, R. & Argyropoulos, D. S. Fractional Precipitation of Softwood Kraft Lignin: Isolation of Narrow Fractions Common to a Variety of Lignins. ACS Sustain. Chem. Eng. 2, 959–968 (2014).       131  49. Sevastyanova, O. et al. Tailoring the molecular and thermo-mechanical properties of kraft lignin by ultrafiltration. J. Appl. Polym. Sci. 131, 40799 (2014). 50. Toledano, A., Serrano, L., Garcia, A., Mondragon, I. & Labidi, J. Comparative study of lignin fractionation by ultrafiltration and selective precipitation. Chem. Eng. J. 157, 93–99 (2010). 51. Dallmeyer, I., Chowdhury, S. & Kadla, J. F. Preparation and characterization of kraft lignin-based moisture-responsive films with reversible shape-change capability. Biomacromolecules 14, 2354–63 (2013). 52. Dallmeyer, I., Lin, L. T., Li, Y., Ko, F. & Kadla, J. F. Preparation and Characterization of Interconnected, Kraft Lignin-Based Carbon Fibrous Materials by Electrospinning. Macromol. Mater. Eng. 299, 540–551 (2014). 53. Choi, D. I. et al. Fabrication of polyacrylonitrile / lignin-based carbon nanofibers for high-power lithium ion battery anodes. 17, 2471–2475 (2013). 54. Jin, J., Yu, B., Shi, Z., Wang, C. & Chong, C. Lignin-based electrospun carbon nanofibrous webs as free-standing and binder-free electrodes for sodium ion batteries. J. Power Sources 272, 800–807 (2014). 55. Liting Lin, Y. L. F. K. K., Lin, L., Li, Y. & Ko, F. K. Fabrication and Properties of Lignin Based Carbon Nanofiber. J. Fiber Bioeng. Informatics 6, 335–347 (2013).       132  56. Ameringer, T. et al. Surface grafting of electrospun fibers using ATRP and RAFT for the control of biointerfacial interactions. Biointerphases 8, 16 (2013). 57. Li, L. & Lukehart, C. M. Synthesis of Hydrophobic and Hydrophilic Graphitic Carbon Nanofiber Polymer Brushes. Chem. Mater. 18, 94–99 (2006). 58. Gao, G., Karaaslan, M. A., Kadla, J. F. & Ko, F. Enzymatic synthesis of ionic responsive lignin nanofibres through surface poly(N-isopropylacrylamide) immobilization. Green Chem. 16, 3890 (2014). 59. Gao, G., Dallmeyer, J. I. & Kadla, J. F. Synthesis of lignin nanofibers with ionic-responsive shells: water-expandable lignin-based nanofibrous mats. Biomacromolecules 13, 3602–10 (2012). 60. Osada, Y., Honda, K. & Ohta, M. Control of water permeability by mechanochemical contraction of poly(methacrylic acid)-grafted membranes. J. Memb. Sci. 27, 327–338 (1986). 61. Park, Y. S., Ito, Y. & Imanishi, Y. Permeation Control through Porous Membranes Immobilized with Thermosensitive Polymer. Langmuir 14, 910–914 (1998). 62. Abu-Lail, N. I., Kaholek, M., LaMattina, B., Clark, R. L. & Zauscher, S. Micro-cantilevers with end-grafted stimulus-responsive polymer brushes for actuation and sensing. Sensors Actuators B Chem. 114, 371–378 (2006).       133  63. Yamato, M., Konno, C., Utsumi, M., Kikuchi, A. & Okano, T. Thermally responsive polymer-grafted surfaces facilitate patterned cell seeding and co-culture. Biomaterials 23, 561–567 (2002). 64. Cunliffe, D., de las Heras Alarcón, C., Peters, V., Smith, J. R. & Alexander, C. Thermoresponsive Surface-Grafted Poly( N − isopropylacrylamide) Copolymers:  Effect of Phase Transitions on Protein and Bacterial Attachment. Langmuir 19, 2888–2899 (2003). 65. Okano, T., Kikuchi, A., Sakurai, Y., Takei, Y. & Ogata, N. Temperature-responsive poly(N-isopropylacrylamide) as a modulator for alteration of hydrophilic/hydrophobic surface properties to control activation/inactivation of platelets. J. Control. Release 36, 125–133 (1995). 66. Akiyama, Y., Kikuchi, A., Yamato, M. & Okano, T. Ultrathin Poly( N -isopropylacrylamide) Grafted Layer on Polystyrene Surfaces for Cell Adhesion/Detachment Control. Langmuir 20, 5506–5511 (2004). 67. Duracher, D., Elaïssari, A., Mallet, F. & Pichot, C. Adsorption of Modified HIV-1 Capsid p24 Protein onto Thermosensitive and Cationic Core−Shell Poly(styrene)−Poly( N -isopropylacrylamide) Particles. Langmuir 16, 9002–9008 (2000). 68. Ionov, L., Stamm, M. & Diez, S. Reversible switching of microtubule motility using thermoresponsive polymer surfaces. Nano Lett. 6, 1982–7 (2006).       134  69. Taniguchi, T., Duracher, D., Delair, T., Elaı̈ssari, A. & Pichot, C. Adsorption/desorption behavior and covalent grafting of an antibody onto cationic amino-functionalized poly(styrene-N-isopropylacrylamide) core-shell latex particles. Colloids Surfaces B Biointerfaces 29, 53–65 (2003). 70. Bromberg, L. Temperature-responsive gels and thermogelling polymer matrices for protein and peptide delivery. Adv. Drug Deliv. Rev. 31, 197–221 (1998). 71. Bergbreiter, D. E. & Caraway, J. W. Thermoresponsive Polymer-Bound Substrates. J. Am. Chem. Soc. 118, 6092–6093 (1996). 72. Bergbreiter, D., Koshti, N., Franchina, J. & Frels, J. Sequestration of Trace Metals Using Water-Soluble and Fluorous Phase-Soluble Polymers Support of this work by the National Science Foundation and the Robert A. Welch Foundation is gratefully acknowledged. Angew. Chem. Int. Ed. Engl. 39, 1039–1042 (2000). 73. Chen, G. & Hoffman, A. S. Graft copolymers that exhibit temperature-induced phase transitions over a wide range of pH. Nature 373, 49–52 (1995). 74. Hong, C.-Y., You, Y.-Z. & Pan, C.-Y. Synthesis of Water-Soluble Multiwalled Carbon Nanotubes with Grafted Temperature-Responsive Shells by Surface RAFT Polymerization. Chem. Mater. 17, 2247–2254 (2005). 75. Sun, T. et al. Reversible switching between superhydrophilicity and superhydrophobicity. Angew. Chem. Int. Ed. Engl. 43, 357–60 (2004).       135  76. Lee, J., Isobe, T. & Senna, M. Preparation of Ultrafine Fe3O4Particles by Precipitation in the Presence of PVA at High pH. J. Colloid Interface Sci. 177, 490–494 (1996). 77. Qi, L., Cölfen, H. & Antonietti, M. Synthesis and Characterization of CdS Nanoparticles Stabilized by Double-Hydrophilic Block Copolymers. Nano Lett. 1, 61–65 (2001). 78. Kim, S.-K., Park, S., Son, M.-K. & Kim, H.-J. Ammonia treated ZnO nanoflowers based CdS/CdSe quantum dot sensitized solar cell. Electrochim. Acta 151, 531–536 (2015). 79. Sudhagar, P. et al. The performance of coupled (CdS:CdSe) quantum dot-sensitized TiO2 nanofibrous solar cells. Electrochem. commun. 11, 2220–2224 (2009). 80. Soenen, S. J. et al. The Effect of Intracellular Degradation on Cytotoxicity and Cell Labeling Efficacy of Inorganic Ligand-Stabilized Colloidal CdSe/CdS Quantum Dots. J. Biomed. Nanotechnol. 11, 631–643 (2015). 81. Min, S.-Y. et al. Electrospun polymer/quantum dot composite fibers as down conversion phosphor layers for white light-emitting diodes. RSC Adv. 4, 11585 (2014). 82. Mondal, K., Ali, M. A., Agrawal, V. V, Malhotra, B. D. & Sharma, A. Highly sensitive biofunctionalized mesoporous electrospun TiO(2) nanofiber based interface for biosensing. ACS Appl. Mater. Interfaces 6, 2516–27 (2014). 83. Zhang, Y. et al. TiO2/BiOI heterostructured nanofibers: electrospinning–solvothermal two-step synthesis and visible-light photocatalytic performance investigation. J. Nanoparticle Res. 16, 2375 (2014).       136  84. Ko, F. et al. Electrospinning of Continuous Carbon Nanotube-Filled Nanofiber Yarns. Adv. Mater. 15, 1161–1165 (2003). 85. Ji, L. & Zhang, X. Fabrication of porous carbon nanofibers and their application as anode materials for rechargeable lithium-ion batteries. Nanotechnology 20, 155705 (2009). 86. Wang, T., Wang, H., Chi, X., Li, R. & Wang, J. Synthesis and microwave absorption properties of Fe–C nanofibers by electrospinning with disperse Fe nanoparticles parceled by carbon. Carbon N. Y. 74, 312–318 (2014). 87. Ren, S., Prakash, R., Wang, D., Chakravadhanula, V. S. K. & Fichtner, M. Fe3O4 anchored onto helical carbon nanofibers as high-performance anode in lithium-ion batteries. ChemSusChem 5, 1397–400 (2012). 88. Ji, L. et al. Porous carbon nanofiber–sulfur composite electrodes for lithium/sulfur cells. Energy Environ. Sci. 4, 5053 (2011). 89. Kong, J. et al. Silicon nanoparticles encapsulated in hollow graphitized carbon nanofibers for lithium ion battery anodes. Nanoscale 5, 2967–73 (2013). 90. Teng, N.-Y., Dallmeyer, I. & Kadla, J. F. Incorporation of Multiwalled Carbon Nanotubes into Electrospun Softwood Kraft Lignin-Based Fibers. J. Wood Chem. Technol. 33, 299–316 (2013).       137  91. Teng, N.-Y., Dallmeyer, I. & Kadla, J. F. Effect of Softwood Kraft Lignin Fractionation on the Dispersion of Multiwalled Carbon Nanotubes. Ind. Eng. Chem. Res. 52, 6311–6317 (2013). 92. Zou, L. et al. A film of porous carbon nanofibers that contain Sn/SnOx nanoparticles in the pores and its electrochemical performance as an anode material for lithium ion batteries. Carbon N. Y. 49, 89–95 (2011). 93. Su, D. S. & Schlögl, R. Nanostructured carbon and carbon nanocomposites for electrochemical energy storage applications. ChemSusChem 3, 136–68 (2010). 94. Kim, Y. K., Cha, S. Il, Hong, S. H. & Jeong, Y. J. A new hybrid architecture consisting of highly mesoporous CNT/carbon nanofibers from starch. J. Mater. Chem. 22, 20554 (2012). 95. Shastri, V. P., Hildgen, P. & Langer, R. In situ pore formation in a polymer matrix by differential polymer degradation. Biomaterials 24, 3133–3137 (2003). 96. Xu, F., Lai, Y., Fu, R. & Wu, D. A facile approach for tailoring carbon frameworks from microporous to nonporous for nanocarbons. J. Mater. Chem. A 1, 5001 (2013). 97. Bazilevsky, A. V, Yarin, A. L. & Megaridis, C. M. Co-electrospinning of core-shell fibers using a single-nozzle technique. Langmuir 23, 2311–4 (2007).       138  98. Buyuktanir, E. A., Frey, M. W. & West, J. L. Self-assembled, optically responsive nematic liquid crystal/polymer core-shell fibers: Formation and characterization. Polymer (Guildf). 51, 4823–4830 (2010). 99. Dror, Y. et al. One Step Production of Polymeric Microtubes by Co electrospinning. Small 3, 1064–1073 (2007). 100. Yang, Y. et al. Structural stability and release profiles of proteins from core-shell poly (DL-lactide) ultrafine fibers prepared by emulsion electrospinning. J. Biomed. Mater. Res. A 86, 374–85 (2008). 101. Lee, K. T., Jung, Y. S. & Oh, S. M. Synthesis of tin-encapsulated spherical hollow carbon for anode material in lithium secondary batteries. J. Am. Chem. Soc. 125, 5652–3 (2003). 102. Yu, Y. et al. Encapsulation of Sn@carbon nanoparticles in bamboo-like hollow carbon nanofibers as an anode material in lithium-based batteries. Angew. Chem. Int. Ed. Engl. 48, 6485–9 (2009). 103. Han, S. O., Son, W. K., Cho, D., Youk, J. H. & Park, W. H. Preparation of porous ultra-fine fibres via selective thermal degradation of electrospun polyetherimide/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fibres. Polym. Degrad. Stab. 86, 257–262 (2004). 104. You, Y. et al. Preparation of porous ultrafine PGA fibers via selective dissolution of electrospun PGA/PLA blend fibers. Mater. Lett. 60, 757–760 (2006).       139  105. Lai, C. et al. Free-standing and mechanically flexible mats consisting of electrospun carbon nanofibers made from a natural product of alkali lignin as binder-free electrodes for high-performance supercapacitors. J. Power Sources 247, 134–141 (2014). 106. Dirican, M., Yanilmaz, M. & Zhang, X. Free-standing polyaniline–porous carbon nanofiber electrodes for symmetric and asymmetric supercapacitors. RSC Adv. 4, 59427–59435 (2014). 107. Tran, C. & Kalra, V. Fabrication of porous carbon nanofibers with adjustable pore sizes as electrodes for supercapacitors. J. Power Sources 235, 289–296 (2013). 108. Kim, B.-H., Yang, K. S. & Ferraris, J. P. Highly conductive, mesoporous carbon nanofiber web as electrode material for high-performance supercapacitors. Electrochim. Acta 75, 325–331 (2012). 109. Tenhaeff, W. E., Rios, O., More, K. & McGuire, M. A. Highly Robust Lithium Ion Battery Anodes from Lignin: An Abundant, Renewable, and Low-Cost Material. Adv. Funct. Mater. 24, 86–94 (2014). 110. Wang, S.-X., Yang, L., Stubbs, L. P., Li, X. & He, C. Lignin-derived fused electrospun carbon fibrous mats as high performance anode materials for lithium ion batteries. ACS Appl. Mater. Interfaces 5, 12275–82 (2013). 111. Jiang, H., Lee, P. S. & Li, C. 3D carbon based nanostructures for advanced supercapacitors. Energy Environ. Sci. 6, 41 (2013).       140  112. Niu, H., Zhang, J., Xie, Z., Wang, X. & Lin, T. Preparation, structure and supercapacitance of bonded carbon nanofiber electrode materials. Carbon N. Y. 49, 2380–2388 (2011). 113. He, S. et al. Supercapacitors based on 3D network of activated carbon nanowhiskers wrapped-on graphitized electrospun nanofibers. J. Power Sources 243, 880–886 (2013). 114. Al-Saleh, M. H. & Sundararaj, U. A review of vapor grown carbon nanofiber/polymer conductive composites. Carbon N. Y. 47, 2–22 (2009). 115. EMI/RFI: Materials and Technologies. <http://www.prnewswire.com/news-releases/emirfi-materials-and-technologies-157294351.html> (access date: July 10,2015) 116. Tong, X. C. Advanced Materials and Design for Electromagnetic Interference Shielding. (Taylor & Francis, 2008). 117. Yang, S., Lozano, K., Lomeli, A., Foltz, H. D. & Jones, R. Electromagnetic interference shielding effectiveness of carbon nanofiber/LCP composites. Compos. Part A Appl. Sci. Manuf. 36, 691–697 (2005). 118. Yang, Y., Gupta, M. C., Dudley, K. L. & Lawrence, R. W. Conductive Carbon Nanofiber-Polymer Foam Structures. Adv. Mater. 17, 1999–2003 (2005). 119. Yang, Y. et al. Electrospun magnetic carbon composite fibers: Synthesis and electromagnetic wave absorption characteristics. J. Appl. Polym. Sci. 127, 4288–4295 (2013).       141  120. Yang, Y., Gupta, M. C., Dudley, K. L. & Lawrence, R. W. Novel Carbon Nanotube−Polystyrene Foam Composites for Electromagnetic Interference Shielding. Nano Lett. 5, 2131–2134 (2005). 121. Zhang, T., Huang, D., Yang, Y., Kang, F. & Gu, J. Influence of iron (III) acetylacetonate on structure and electrical conductivity of Fe3O4/carbon composite nanofibers. Polymer (Guildf). 53, 6000–6007 (2012). 122. Ohlan, A., Singh, K., Chandra, A. & Dhawan, S. K. Microwave absorption properties of conducting polymer composite with barium ferrite nanoparticles in 12.4–18 GHz. Appl. Phys. Lett. 93, 053114 (2008). 123. Liu, J. R. et al. Gigahertz range electromagnetic wave absorbers made of amorphous-carbon-based magnetic nanocomposites. J. Appl. Phys. 98, 054305 (2005). 124. Micheli, D., Apollo, C., Pastore, R. & Marchetti, M. X-Band microwave characterization of carbon-based nanocomposite material, absorption capability comparison and RAS design simulation. Compos. Sci. Technol. 70, 400–409 (2010). 125. Panels, J. E. et al. Synthesis and characterization of magnetically active carbon nanofiber/iron oxide composites with hierarchical pore structures. Nanotechnology 19, 455612 (2008).       142  126. Zhang, T., Huang, D., Yang, Y., Kang, F. & Gu, J. Fe3O4/carbon composite nanofiber absorber with enhanced microwave absorption performance. Mater. Sci. Eng. B 178, 1–9 (2013). 127. Kim, T.-H. et al. The Current Move of Lithium Ion Batteries Towards the Next Phase. Adv. Energy Mater. 2, 860–872 (2012). 128. Wakihara, M., Goodenough, J. B. & Yamamoto, O. Lithium Ion Batteries: Fundamentals and Performance. (John Wiley & Sons Canada, Ltd, 1998). 129. Xu, K. Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries. Chem. Rev. 104, 4303–4418 (2004). 130. Marom, R., Amalraj, S. F., Leifer, N., Jacob, D. & Aurbach, D. A review of advanced and practical lithium battery materials. J. Mater. Chem. 21, 9938 (2011). 131. Agrawal, R. C. & Pandey, G. P. Solid polymer electrolytes: materials designing and all-solid-state battery applications: an overview. J. Phys. D. Appl. Phys. 41, 223001 (2008). 132. Zheng, H., Qu, Q., Zhang, L., Liu, G. & Battaglia, V. S. Hard carbon: a promising lithium-ion battery anode for high temperature applications with ionic electrolyte. RSC Adv. 2, 4904 (2012). 133. Ozawa, K. Lithium Ion Rechargeable Batteries: Materials, Technology, and New Applications. (John Wiley & Sons, 2012).       143  134. Kim, C. et al. Fabrication of Electrospinning-Derived Carbon Nanofiber Webs for the Anode Material of Lithium-Ion Secondary Batteries. Adv. Funct. Mater. 16, 2393–2397 (2006). 135. Ji, L., Lin, Z., Alcoutlabi, M. & Zhang, X. Recent developments in nanostructured anode materials for rechargeable lithium-ion batteries. Energy Environ. Sci. 4, 2682 (2011). 136. Kim, S.-S., Kadoma, Y., Ikuta, H., Uchimoto, Y. & Wakihara, M. Electrochemical Performance of Natural Graphite by Surface Modification Using Aluminum. Electrochem. Solid-State Lett. 4, A109 (2001). 137. Hwang, T. H., Lee, Y. M., Kong, B.-S., Seo, J.-S. & Choi, J. W. Electrospun core-shell fibers for robust silicon nanoparticle-based lithium ion battery anodes. Nano Lett. 12, 802–7 (2012). 138. Fratzl, P. & Weinkamer, R. Nature’s hierarchical materials. Prog. Mater. Sci. 52, 1263–1334 (2007). 139. Burgert, I. & Fratzl, P. Actuation systems in plants as prototypes for bioinspired devices. Philos. Trans. A. Math. Phys. Eng. Sci. 367, 1541–57 (2009). 140. Fratzl, P. & Barth, F. G. Biomaterial systems for mechanosensing and actuation. Nature 462, 442–8 (2009). 141. Kosidlo, U. et al. Nanocarbon based ionic actuators—a review. Smart Mater. Struct. 22, 104022 (2013).       144  142. Ma, M., Guo, L., Anderson, D. G. & Langer, R. Bio-inspired polymer composite actuator and generator driven by water gradients. Science 339, 186–9 (2013). 143. Zhao, Q. et al. An instant multi-responsive porous polymer actuator driven by solvent molecule sorption. Nat. Commun. 5, 4293 (2014). 144. Li, S., Meng Lin, M., Toprak, M. S., Kim, D. K. & Muhammed, M. Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications. Nano Rev. 1, (2010). 145. Dong, F. et al. Fabrication of semiconductor nanostructures on the outer surfaces of polyacrylonitrile nanofibers by in-situ electrospinning. Mater. Lett. 61, 2556–2559 (2007). 146. Katepetch, C. & Rujiravanit, R. Synthesis of magnetic nanoparticle into bacterial cellulose matrix by ammonia gas-enhancing in situ co-precipitation method. Carbohydr. Polym. 86, 162–170 (2011). 147. Sichani, G. N., Morshed, M., Amirnasr, M. & Abedi, D. In situ preparation, electrospinning, and characterization of polyacrylonitrile nanofibers containing silver nanoparticles. J. Appl. Polym. Sci. 116, 1021–1029 (2009). 148. Nataraj, S. K., Kim, B.-H., Yang, K. S. & Woo, H.-G. In-situ deposition of iron oxide nanoparticles on polyacrylonitrile-based nanofibers by chemico-thermal reduction method. J. Nanosci. Nanotechnol. 10, 3530–3 (2010).       145  149. Panels, J. E. et al. Synthesis and characterization of magnetically active carbon nanofiber / iron oxide composites with hierarchical pore structures. Nanotechnology 19, (2008). 150. Mörck, R. & Yoshida, H. Fractionation of kraft lignin by successive extraction with organic solvents. 1. Functional groups (13) C-NMR-spectra and molecular weight distributions. Holzforschung 40, 51–60 (1986). 151. Sarkanen, S., Teller, D. C., Stevens, C. R. & McCarthy, J. L. Lignin. 20. Associative interactions between kraft lignin components. Macromolecules 17, 2588–2597 (1984). 152. Connors, W. J., Sarkanen, S. & McCarthy, J. L. Gel Chromatography and Association Complexes of Lignin. Holzforschung 34, 80–85 (1980). 153. Lee, S. Y. et al. Porous multi-walled carbon nanotubes by using catalytic oxidation via transition metal oxide. Microporous Mesoporous Mater. 194, 46–51 (2014). 154. Hyeon, T., Lee, S. S., Park, J., Chung, Y. & Na, H. Bin. Synthesis of Highly Crystalline and Monodisperse Maghemite Nanocrystallites without a Size-Selection Process. J. Am. Chem. Soc. 123, 12798–12801 (2001). 155. Ferrari, A. & Robertson, J. Interpretation of Raman spectra of disordered and amorphous carbon. Phys. Rev. B 61, 14095–14107 (2000). 156. Hernadi, K. et al. Catalytic production of carbon nanofibers over iron carbide doped with Sn2+. Appl. Catal. A Gen. 228, 103–113 (2002).       146  157. He, Z. et al. Iron Catalysts for the Growth of Carbon Nanofibers: Fe, Fe 3 C or Both? Chem. Mater. 23, 5379–5387 (2011). 158. Frank, E., Steudle, L. M., Ingildeev, D., Spörl, J. M. & Buchmeiser, M. R. Carbon fibers: precursor systems, processing, structure, and properties. Angew. Chem. Int. Ed. Engl. 53, 5262–98 (2014). 159. Sergiienko, R., Shibata, E., Kim, S., Kinota, T. & Nakamura, T. Nanographite structures formed during annealing of disordered carbon containing finely-dispersed carbon nanocapsules with iron carbide cores. Carbon N. Y. 47, 1056–1065 (2009). 160. Sun, R., Sun, X. F. & Xu, X. P. Effect of ultrasound on the physicochemical properties of organosolv lignins from wheat straw. J. Appl. Polym. Sci. 84, 2512–2522 (2002). 161. Vasquez, H., Espinoza, L., Lozano, K., Foltz, H. & Yang, S. Simple device for electromagnetic interference shielding effectiveness measurement. EMC IEEE EMC Soc. Newsl. 220, 62–68 (2009). 162. Hasar, U. C. Thickness-independent automated constitutive parameters extraction of thin solid and liquid materials from waveguide measurements. Prog. Electromagn. Res. 92, 17–32 (2009). 163. Crespo, M., Méndez, N., González, M., Baselga, J. & Pozuelo, J. Synergistic effect of magnetite nanoparticles and carbon nanofibres in electromagnetic absorbing composites. Carbon N. Y. 74, 63–72 (2014).       147  164. Watts, P. C. P., Ponnampalam, D. R., Hsu, W. K., Barnes, A. & Chambers, B. The complex permittivity of multi-walled carbon nanotube–polystyrene composite films in X-band. Chem. Phys. Lett. 378, 609–614 (2003). 165. Gui, X. et al. Optimization of electromagnetic matching of Fe-filled carbon nanotubes/ferrite composites for microwave absorption. J. Phys. D. Appl. Phys. 42, 075002 (2009). 166. Li, G., Xie, T., Yang, S., Jin, J. & Jiang, J. Microwave Absorption Enhancement of Porous Carbon Fibers Compared with Carbon Nanofibers. J. Phys. Chem. C 116, 9196–9201 (2012). 167. Huang, Y. et al. Effect of Pore Morphology on the Dielectric Properties of Porous Carbons for Microwave Absorption Applications. J. Phys. Chem. C 118, 26027–26032 (2014). 168. Sun, G., Dong, B., Cao, M., Wei, B. & Hu, C. Hierarchical Dendrite-Like Magnetic Materials of Fe 3 O 4 , γ-Fe 2 O 3 , and Fe with High Performance of Microwave Absorption. Chem. Mater. 23, 1587–1593 (2011). 169. Liu, J. et al. Double-Shelled Yolk–Shell Microspheres with Fe 3 O 4 Cores and SnO 2 Double Shells as High-Performance Microwave Absorbers. J. Phys. Chem. C 117, 489–495 (2013).       148  170. Liu, J. et al. Hierarchical Fe3O4@TiO2 yolk-shell microspheres with enhanced microwave-absorption properties. Chemistry 19, 6746–52 (2013). 171. Zhang, X. F., Huang, H. & Dong, X. L. Core/Shell Metal/Heterogeneous Oxide Nanocapsules: The Empirical Formation Law and Tunable Electromagnetic Losses. J. Phys. Chem. C 117, 8563–8569 (2013). 172. Chen, L. F., Ong, C. K., Neo, C. P., Varadan, V. V. & Varadan, V. K. Microwave Electronics: Measurement and Materials Characterization. 19, (John Wiley & Sons, 2004). 173. Yan, N. et al. Fe₂O₃ nanoparticles wrapped in multi-walled carbon nanotubes with enhanced lithium storage capability. Sci. Rep. 3, 3392 (2013). 174. Wu, M.-S., Ou, Y.-H. & Lin, Y.-P. Electrodeposition of iron oxide nanorods on carbon nanofiber scaffolds as an anode material for lithium-ion batteries. Electrochim. Acta 55, 3240–3244 (2010). 175. Yan, N. et al. Fe2O3₃ nanoparticles wrapped in multi-walled carbon nanotubes with enhanced lithium storage capability. Sci. Rep. 3, 3392 (2013). 176. Hang, B. T., Okada, S. & Yamaki, J. Effect of binder content on the cycle performance of nano-sized Fe2O3-loaded carbon for use as a lithium battery negative electrode. J. Power Sources 178, 402–408 (2008).       149  177. Chen, J., Xu, L., Li, W. & Gou, X. Fe2O3 Nanotubes in Gas Sensor and Lithium-Ion Battery Applications. Adv. Mater. 17, 582–586 (2005). 178. Wu, Y., Zhu, P., Reddy, M. V, Chowdari, B. V. R. & Ramakrishna, S. Maghemite nanoparticles on electrospun CNFs template as prospective lithium-ion battery anode. ACS Appl. Mater. Interfaces 6, 1951–8 (2014). 179. Hang, B. T., Doi, T., Okada, S. & Yamaki, J. Effect of carbonaceous materials on electrochemical properties of nano-sized Fe2O3-loaded carbon as a lithium battery negative electrode. J. Power Sources 174, 493–500 (2007). 180. Ito, A., Zhao, L., Okada, S. & Yamaki, J. Synthesis of nano-Fe 3 O 4 -loaded tubular carbon nanofibers and their application as negative electrodes for Fe / air batteries. J. Power Sources 196, 8154–8159 (2011). 181. Taberna, P. L., Mitra, S., Poizot, P., Simon, P. & Tarascon, J.-M. High rate capabilities Fe3O4-based Cu nano-architectured electrodes for lithium-ion battery applications. Nat. Mater. 5, 567–73 (2006). 182. Wang, L., Yu, Y., Chen, P. C., Zhang, D. W. & Chen, C. H. Electrospinning synthesis of C / Fe 3 O 4 composite nanofibers and their application for high performance lithium-ion batteries. 183, 717–723 (2008).       150  183. Cabana, J., Monconduit, L., Larcher, D. & Palacín, M. R. Beyond intercalation-based Li-ion batteries: the state of the art and challenges of electrode materials reacting through conversion reactions. Adv. Mater. 22, E170–92 (2010). 184. Zhou, G., Li, F. & Cheng, H.-M. Progress in flexible lithium batteries and future prospects. Energy Environ. Sci. 7, 1307 (2014). 185. Wang, X. et al. Flexible Energy-Storage Devices: Design Consideration and Recent Progress. Adv. Mater. 4763–4782 (2014).  186. Jabbour, L. et al. Flexible cellulose/LiFePO4 paper-cathodes: toward eco-friendly all-paper Li-ion batteries. Cellulose 20, 571–582 (2012). 187. Wang, Y., Li, B., Ji, J., Eyler, A. & Zhong, W.-H. A Gum-Like Electrolyte: Safety of a Solid, Performance of a Liquid. Adv. Energy Mater. 3, 1557–1562 (2013). 188. Pushparaj, V. Flexible energy storage devices based on nanocomposite paper. Proc. Natl. Acad. Sci. U. S. A. 104, 13574–13577 (2007). 189. Alibaba. Price for pyrrole. at <http://www.alibaba.com/product-detail/Pyrrole-109-97-7_1409102142.html?spm=a2700.7724857.35.1.UTBosT> (acess date: July 10 2015) 190. Heiningen, A. van. Converting a kraft pulp mill into an integrated forest biorefinery. Pulp Pap. Canada 107, T141–T146 (2006). 191. Polymorphism. (Wiley-VCH Verlag GmbH & Co. KGaA, 2006).        151  192. Pal, S. K., Peon, J., Bagchi, B. & Zewail, A. H. Biological Water:  Femtosecond Dynamics of Macromolecular Hydration. J. Phys. Chem. B 106, 12376–12395 (2002).           152  Appendix  1. Molecular weight measurement of fractionated lignin To measure the molecular weight of F4, lignin was firstly acetylated to get dissolved into the solvent THF which is the solvent used in the GPC. To verify if the all the phenolic and aliphatic hydroxyl groups were acetylated, FT-IR and NMR were run to check the change of the amount of the phenolic hydroxyl group and aliphatic hydroxyl group. Then GPC and light scattering techniques were used to measure the molecular weight of F4. Lignin acetylation reaction was conducted as follows. 200 mg F4SKL was acetylated with 4 ml acetic anhydride and 4ml pyridine at room temperature for 48 hours. Dilute this solution with 200~300 ml ice water and leave it for 1 hour to precipitate before the filtration. While filtering, 200ml HCl, 100ml NaHCO3, and water were used to wash the acetylated lignin. Then, leave it overnight to air dry before the further pistol dry. Take the acetylated F4 to run the whole process again to collect re-acetylated F4. Proton nuclear magnetic resonance (1HNMR) was done for acetylated and re-acetylated F4SKL.The spectrum was recorded in chloroform solution. A solution containing the standard material 4-Nitrobenzaldehyde (1.7mg) and acetylated lignin in “100%” CDCl3 (500 ml) was prepared. The 1H-NMR spectra were recorded. Manual phasing and baseline corrections were done and an integration file was created so the same integration regions were used for each spectrum. FT-IR was used to verify the lignin was firstly acetylated. Then GPC and light scattering techniques were used to measure the molecular weight of the fractionation 4 of softwood Kraft lignin.       153    Figure A-1 Comparison of 24 hours acetylation and 48 hours acetylation for F4   Figure A-2 24hours acetylation F4 1H-NMR for OH calculation 4000 .0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.00.000.10.20.30.40.50.60.70.80.91.01.11.21.31.41.51.61.71.73cm-1A 24 hours 48 hours       154   Figure A-3 48hours acetylation F4 1H-NMR for OH calculation  Table A-1 lists the regions integrated for each spectrum. FT-IR (Figure A-1) and NMR (Figure A-2 and A-3) were run for acetylated and re-acetylated F4SKL. Quantitative estimates of the various proton containing functional groups were made by performing the following calculation. The signal area of the standard material signal, which was due to the 1.7mg 4-Nitrobenzaldehyde, was integrated and calibrated to 1.0. Since this molecule contains one proton and has a molecular weight of 151.03 g/mol. 2.0195x10-5 was the number of moles of H present in the internal standard in the sample. Since the integration region of the internal standard was calibrated to 1.0, each unit area in the spectrum is equal to 20.195 μmoles of H. For each spectrum this value (or factor) is multiplied by the integration region of interest and divided by the weight of the lignin sample. For example, if the lignin sample weighed 7.64 mg and the integration of the aromatic region equaled 3.590 then 9.48 mmol  aromatic H /g lignin are       155  present in the lignin sample. Thus 3.16 mmol/g lignin phenolic hydroxyl groups are present in lignin. Table A-2 lists the calculated amount of the phenolic hydroxyl group and aliphatic hydroxyl group from NMR.  Table A-1 Functional group frequency and integration regions used for the quantitative 1HNMR spectra of lignin acetates Structure or functional group integration region (ppm) standard material 10.4~10.2 lignin aromatic H 8.0-6.2 lignin -OCH3 4.2-3.6 aromatic acetate 2.6~2.2 aliphatic acetate 2.2~1.6  Table A-2 The calculated amount of the phenolic hydroxyl group and aliphatic hydroxyl group from NMR  acetylated F4SKL Re - acetylated F4SKL phenolic hydroxyl group 3.59 mmol/g 2.90 mmol/g aliphatic hydroxyl group 4.48 mmol/g 5.13 mmol/g  NMR studies suggest that after twice acetylation, the reaction change the amount of hydroxyl group but it is within the error. One acetylation reaction is enough for acetylating F4.  GPC indicates the average molecular weight of F4 is Mw= 35215, and Mn=16055.       156  2. SEM and TEM of lignin-based composite carbon nanofibres 10A-35F4-250-1-60-900 Flexible 10A-35F4-250-1-60-1000 Flexible     Figure A-4 SEM and TEM images of 10A 35 carbonized electrospun fibres obtained at different temperature 900 and 1000 ˚C (10A35F4-250-1-60)      a b c d       157      Figure A-5 SEM and TEM images of carbon nanofibre electrospun from solutions of 3%IAA/35%F4, thermostabilized at 250˚C with heating rate of 1˚C/min, carbonized at 700 (3A700) (a,b), 800 (3A800) (c,d), 900 (3A900) (e,f) and 1000 ˚C (3A1000) (g,h)      g h e f a b       158        h g c d e f       159    Figure A-6 SEM and TEM images of carbon nanofibre electrospun from solutions of F4, thermolstablized at 250˚C with heating rate of 1˚C/min, carbonized at 1000˚C with different IAA concentration,1% (a,b), 3% (c,d), 5%(e,f), 10% (g,h)  and 20% (i,j)        i j a b c d       160        Figure A-7 SEM and TEM images of carbon nanofibre electrospun from solutions of F4, thermolstablized at 250˚C with heating rate of 5˚C/min, carbonized at 1000˚C with different IAA concentration,1% (a,b), 3% (c,d), 5%(e,f), 10% (g,h)  and 20% (i,j)    5 0 0  n mi e g f h j       161     Figure A-8 SEM images of composite carbon nanofibre (1000˚C) from solution of 3%IAA/35%F4 with different thermostabilization  heating rate:(a) 1 ˚C/min, (b) 3 ˚C/min and (c) 5 ˚C/min      a b c       162      Figure A-9 Representative STEM-HAADF image of lignin carbon nanofibre (10A35F4-250-1-60-1000-10-60) with the in-situ synthesized nanoparticles and mapping of carbon, iron and oxygen        163      Figure A-10 Representative TEM images of lignin carbon nanofibre with the in-situ synthesized nanoparticles 20A35F4-250-5-60-1000-10-60  5 0 0  n m425.84 nm1 0  1 / n m2 0 0  n m5 0  n m      164            165    Figure A-11 Representative STEM-HAADF image of lignin carbon nanofibre 20A35F4-250-5-60-1000-10-60 with the in-situ synthesized nanoparticles and mapping of carbon, iron, oxygen and sulfur                 166  3. XRD of lignin-based composite carbon nanofibres   Figure A-12 XRD pattern of CNF obtained from electrospun fibres with different amount of 1% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C          167   Figure A-13 XRD pattern of CNF obtained from electrospun fibres with different amount of 3% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C       168   Figure A-14 XRD pattern of CNF obtained from electrospun fibres with different amount of 5% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C       169   Figure A-15 XRD pattern of CNF obtained from electrospun fibres with different amount of 10% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C       170   Figure A-16 XRD pattern of CNF obtained from electrospun fibres with different amount of 20% IAA with 1˚C/min at 250˚C for 60min and carbonized at 1000˚C         171   Figure A-17 XRD pattern of CNF obtained from electrospun fibres with different amount of 1% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C        172   Figure A-18 XRD pattern of CNF obtained from electrospun fibres with different amount of 3% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C       173   Figure A-19 XRD pattern of CNF obtained from electrospun fibres with different amount of 5% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C       174   Figure A-20 XRD pattern of CNF obtained from electrospun fibres with different amount of 10% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C       175   Figure A-21 XRD pattern of CNF obtained from electrospun fibres with different amount of 20% IAA with 5˚C/min at 250˚C for 60min and carbonized at 1000˚C       176   Figure A-22 XRD pattern of CNF obtained from electrospun fibres with different amount of 3% IAA with 3˚C/min at 250˚C for 60min and carbonized at 1000˚C 4. DSC of F4 and F1-3       177   Figure A-23 DSC of F1-3 powder  Figure A-24 mDSC of F4       178   Figure A-25 DSC of acetylated-F4  

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