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Ghaffarkhah, Ahmadreza

University of British Columbia

This thesis explores how structural design influences the performance of advanced materials in electromagnetic interference (EMI) shielding and strain/pressure sensing. Four material categories—laminated, 3D printed, polymer nanocomposites, and aerogels—are explored using various fabrication methods. The journey begins with the synthesis and characterization of foundational nanomaterials, such as Ti₃C₂Tₓ, graphene oxide (GO), and magnetic GO (mGO). These materials form the basis of our structures. Laminated structures are then created through versatile drop-casting, yielding highly conductive Ti₃C₂Tₓ /PEDOT:PSS films. This approach ensures uniformity, cost-effectiveness, and ease of production. A wet-transfer technique is introduced to adapt these films to intricate shapes, ensuring scalability for EMI shielding applications. The development continues with laminated 3D-printed structures tailored for EMI shielding and strain sensing. Challenges associated with extrusion printing, including resolution and the need for high electrical conductivity and mechanical flexibility, are addressed. This phase results in additive-free inks for high-resolution extrusion printing and composite structures with outstanding electrical conductivity and mechanical flexibility. Notably, the material consumption for these 3D-printed structures is nearly 75% lower than that of traditional laminated structures, resulting in significantly reduced fabrication costs essential for large-scale applications. Next, the thesis delves into aerogel-based conductive materials and polymer nanocomposites. A novel "liquid streaming" approach is introduced for aerogel fabrication, using nanoparticle surfactants to stabilize aqueous suspensions of Ti₃C₂Tₓ/GO in a nonpolar medium. These aerogels offer simplicity, reduced pre-processing, exceptional EMI shielding effectiveness, specific EMI shielding effectiveness, and low density, enhanced by micro- and macro-scale porosities that significantly improve absorption characteristics. The final chapter presents Janus liquids, enabling the creation of responsive aerogels customized for piezoresistive sensing, human motion monitoring, and EMI shielding with absorption-dominant characteristics. This research deepens our understanding of structural design's influence on EMI shielding and pressure sensing and showcases the potential of multifunctional materials for future electronic and sensing applications.

Text

2023-12-14

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86948

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/