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Zhang, Yifan

University of British Columbia

To address the increasing environmental concerns related to solid waste disposal, specifically non-biodegradable electronic sensors laden with heavy metals, this thesis investigates an environmentally friendly substitute. We delve into the potential of cellulose, the most abundant natural polymer, in developing biodegradable and flexible 3D sensing materials. In the first part, we create a super-stretchable and self-healing all-cellulose hydrogel. Our technique involves molecular engineering of cellulose chains and their hydrogen bonding network through periodate oxidation ring-opening reactions, followed by borohydride reduction. This innovative approach alleviates chain rigidity, enhances chain mobility, and leads to the production of hydrogels that showcase record-breaking stretchability, quick self-healing properties, and non-Newtonian behavior. The hydrogels are further tested as human motion sensors and ECG electrodes, marking significant strides in wearable technology. The second part of this work presents a super-elastic Carbon Black (CB) coated cellulose sub-micron fiber aerogel sensor, which is developed through ice-templating and electrostatic assembly. By controlling temperature, the 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNF) assembles into a 3D sub-micron fiber (SMF) network, achieving elasticity in the aerogel. The CB forms a conductive network structure on the TOCNF SMF surface through electrostatic adsorption. This unique strategy results in a SMF/CB aerogel with super-elasticity, high sensitivity, fast response and recovery times, which opens new avenues for wearable sensor applications. In summary, this thesis advocates for the potential of cellulose in developing eco-friendly, high-performance sensors, offering key insights into cellulose-based hydrogel and aerogel that manifest extraordinary properties, with potential applications in wearable technology and human health monitoring.

Text

2024-09-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85696

Forestry

University of British Columbia

UBCV

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