| Author: | Lam, Yin Tung |
| Title: | Bio-inspired catechol chemistry for material functionalization |
| Advisors: | Xin, H. John (SFT) Fei, Bin (SFT) |
| Degree: | Ph.D. |
| Year: | 2023 |
| Subject: | Sewage -- Purification Catechol Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xx, 168 pages : color illustrations |
| Language: | English |
| Abstract: | Sustainable approaches for material functionalization based on catechol chemistry are proposed. In this thesis, three studies related to catechol-based pigmentation, catechol-induced tunable surface charges for wastewater treatment and catechol-enhanced functional material for energy generation will be discussed. These studies have demonstrated the versatile functionalities of the catechol moiety and its potential for a wide range of applications. For the study of catechol-based pigmentation, the heteromolecular pigmentations using naturally derived catechol and amino acids were developed for sustainable textile coloration through the inspiration of the strong adhesion feature of DOPA discovered in mussel adhesive proteins. A diverse range of colour could be generated via biomimicking pigmentation with different combinations of catechol and amino at room temperature. The pigmentation could be finely tuned to form various attractive coatings on textile materials. The findings showed that a gram of material could be dyed with milligrams of reactants, and the heteromolecular pigmentations could endow fabrics a wider colour gamut ranging from brown to blue. The catechol-amino acid pigments demonstrated good fastness properties, low toxicity, and highly reproducible colours on textile substrates. This catechol-based pigmentation can also be realized in a more environmentally friendly way with cold pad-batch method, which further minimizes both water and energy consumption. The results of the study open a novel sustainable direction for coloration of textile materials. For the study of catechol-induced tunable surface charges, magnetic polydopamine (PDA) nanocomposites were prepared with a facile and sustainable synthetic method. The assynthesized polymer-based hybrid composites inherited the intrinsic adhesiveness contributed by catechol and amino moieties of PDA as well as the magnetic property of Fe3O4. With the unique properties of PDA, the surface charges of Fe3O4@PDA could be easily tuned by pH for smart adsorption-desorption behaviors. Four commercially available dyestuffs including crystal violet, rhodamine B, direct blue 71 and orange G with different structures and surface charges in solution were selected to investigate the adsorption ability and universality of Fe3O4@PDA in wastewater treatment. It was found that the nanocomposites could successfully adsorb these cationic and anionic dyes under suitable pH conditions. This confirmed the ability of these nanoadsorbents for the removal of common textile dyes. The dispersed magnetic nanoadsorbents also demonstrated the ease of collection from dye mixtures, and the possibility in reusing them for several cycles. Selective dye separation was found to be achievable via simple charge control without large consumption of organic solvent and energy. These bio-inspired nanocomposite adsorbents have shown high potential in wastewater treatment and selective recovery of dye waste, especially for wastewater containing ionic dyes. For the study of catechol-enhanced functional material, polylactic acid (PLA) film with catechol-coated zeolitic imidazolate framework-8 (ZIF-8) composite material was fabricated as a tribopositive layer for sustainable triboelectric energy application. Catechol coating served as an interfacial layer between the ZIF-8 filler and PLA polymer matrix, yielding a composite material in a more homogeneous state. It was found that the presence of catechol layer on fillers could endow the PLA composite film with enhanced electrical performance of the polymer materials, more uniform distribution of nanofillers, improved tensile property, and antibacterial effect. The catechol-enhanced film could effectively power electronic devices. The effectiveness of catechols for the modulation of interfacial interaction between fillers and substrate was preliminary confirmed. This work gives an idea of employing interfacial coupling effect of catechols for the improvement of doping metal-organic framework nanoparticles into polymer matrix, facilitating the development of multifunctional dielectric materials for triboelectric applications. |
| Rights: | All rights reserved |
| Access: | open access |
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