| Author: | Hua, Jiachuan |
| Title: | Development of functional fibers from tough hydrogels |
| Advisors: | Fei, Bin (ITC) |
| Degree: | Ph.D. |
| Year: | 2022 |
| Subject: | Fibers Colloids Smart materials Hong Kong Polytechnic University -- Dissertations |
| Department: | Institute of Textiles and Clothing |
| Pages: | xvii, 136 pages : color illustrations |
| Language: | English |
| Abstract: | Functional hydrogel fibers are highly desirable for smart textiles. Herein, three systems were investigated for functional fiber development. Firstly, shape memory gel fibers were synthesized from acrylamide, iota-carrageenan and bacterial cellulose by polymerization in template and drying at stretch. Super-tough polyacrylamide/iota-carrageenan double-network hydrogels were synthesized via a one-pot radical polymerization and strengthened by incorporating bacterial cellulose microclusters, through the intermolecular hydrogen bonds and topological interlock between microclusters and polymer network. Such hydrogels were able to withstand over 200 kPa of tensile stress, or be stretched over 27 times of initial length, and reached a high toughness of ~2000 kJ/m3. By tension-drying and post-annealing treatments on the strongest hydrogel, dry strands were fabricated to withstand over 100 MPa of tensile stress. Moreover, these strands presented water-stimulated shape memory by a recovery ratio of 84.3% in 4 minutes. Based on these characteristics, this super-tough hydrogel may serve as smart textile or actuator for a variety of applications. Secondly, wound dressing gel fibers were fabricated from polyacrylamide and alginate by continuous wet spinning and electron beam crosslinking. The irradiation induced covalent crosslinking was proved by the increase of gel fraction and crosslinking density. Higher electron beam dosage and drawing ratio contributed to strength but limited stretchability of irradiated fibers. Such fibers reached a high tensile strength over 12 MPa and Young's modulus exceeding 130 MPa that are stronger than representative hydrogel fibers and even comparable with natural tissues. Via facile post-drawing and drying process on irradiated fiber, shape memory fiber was manufactured and exhibited rapid shape recovery behavior in response to water. Wound dressing woven by such fiber presented water-stimulated length contraction on warp direction and fiber space closure behavior that exerted compression on wound and prevented contamination. The in vivo validation of shape memory dressing demonstrated its good biocompatibility, as well as the facilitation on hemostasis and wound healing which is better than commercialized dressing. This facile fabrication opens a new avenue for shape memory gel fiber and fabric which are promising for textile actuator and tissue replacement. Thirdly, photonic crystal gel fibers were constructed from waterborne polyurethane and paramagnetic core-shell particles by continuous spinning and UV-curing in magnetic field. Priorly, we successfully synthesized magnetic-responsive colloidal nanoparticles via a one-step solvothermal reaction and further tuned their structure via polydopamine coating. Via UV initiated radical polymerization between chains of polyurethane-acrylate prepolymer, photonic crystal gel membrane was fabricated with brilliant structural color and mechanochromic performance. A facile and scalable one-step reactive spinning system was constructed for the spinning of photonic crystal gel fibers with programmable colors. Such nanocomposite gel fiber presented significantly strengthened tensile properties and electromagnetic shielding performance. The mechanochromic and solvatochromic properties of typical fibers were studied and applied in force sensing and pattern printing. These photonic crystal gel fibers may serve as flexible sensors and intelligent devices. |
| Rights: | All rights reserved |
| Access: | open access |
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