Design of Functional Coating on Cellulose Nanocrystals for Advanced Applications
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As a result of the increasing demand for high-performance, sustainable consumer products, renewable materials with benign characteristics are receiving considerable attention. Among many renewable materials, cellulose nanocrystal (CNC) is recognized as a promising candidate for the development of functional nanomaterials for various applications. CNC possesses many attractive characteristics, and it can be easily modified to produce the desired functionalities for a specific application. The modification of CNC can be achieved via chemical or physical pathways by utilizing the abundant surface hydroxyl groups and strong surface charge. The most straightforward CNC modification method is to generate the required functional coating rather than using other complicated chemical modification methods. Therefore, this thesis focuses on designing various functional coatings on the CNC surface and explores its potential applications. In the initial part of the research, gold nanoshell coated CNC was successfully fabricated using two different approaches, namely a seed-mediated ex-situ method and an in-situ one-pot syntheses. Especially, a novel in-situ one-pot synthesis approach successfully simplified the CNC gold nanoshell synthesis by precisely controlling the electrostatic interaction between the chemical species and result in uniform gold shell coating on CNC. In the following study, Poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer coated CNC was synthesized and employed to fabricate a highly stretchable, sensitive, and self-healing strain sensor for human motion detection. Compared to the pure PEDOT sensor (gauge factor = 9.35), CNC/PEDOT sensor demonstrated higher sensitivity (GF = 21.25) due to the CNC template, lowering the electrical percolation onset of the composite and improving PEDOT dispersity within the hydrophilic PVA matrix. Also, glycerol plasticizer enable the sensor to have skin-like modulus and the prepared sensor effectively monitor a range of human motions, such as complex joint bending motions and subtle muscle motions. A rapid and effective antibacterial system based on inexpensive and sustainable Cu2O nanoparticle-coated CNC was developed. CNC template allows stable and small size Cu2O nanoparticle synthesis and CNC/PEI/Cu2O demonstrated higher antimicrobial performance than CNC/PEI/Cu, which is attributed to the high toxicity of the Cu+ ion. It was then successfully coated onto fabrics using a simple spray coating method, and the prepared antibacterial fabrics rapidly eliminated the bacteria in less than 3 min for E. coli and 10 min for S. aureus while it maintained the breathability and filtration properties of the original fabrics. In conclusion, this doctoral thesis describes the development of functional coating on CNC, providing novel properties and synergistic effects with pristine CNC. It demonstrated the limitless potential of CNC by expanding its conventional research and application fields.
Cite this version of the work
Yebin Lee (2022). Design of Functional Coating on Cellulose Nanocrystals for Advanced Applications. UWSpace. http://hdl.handle.net/10012/18762