Hydrophilically modified fibrous materials: Synthesis and application

This dissertation explores strategies for making fibrous materials with enhanced hydrophilicity and investigates the applications of these materials for enzyme immobilization. Fibrous materials are intrinsically porous and have the advantages of high specific areas, superior mechanical and excellent handling properties. These properties are of particular interest in some biomedical applications, such as tissue engineering, drug delivery, and immobilization of antigens and proteins. Recent progress in intelligent hydrogels gives optimism to make fibers which are able to self-regulate structure and performance in response to environmental variation. Herein, several approaches of introducing intelligent hydrophilic groups onto fibrous materials are reported.; A review of the relevant techniques and hydrophilic polymers including their synthesis, property, and application is given in Chapter 1. Chapter 2a describes the synthesis of intelligent hydrogels from N-isopropylacrylamide (NIPAAm) and sodium acrylate (SA) in the form of copolymers and interpenetrating networks (IPNs). The swelling and thermal properties of the hydrogels are studied to gain insights into the polymer-polymer and polymer-solvent interactions within the different network structures. In Chapter 2b, poly(NIPAAm- co-SA) copolymer hydrogels are physically attached to the cellulose and polypropylene nonwovens by an in situ free radical polymerization. Both water absorbency and pore structure of these hydrogel-fabric hybrids are regulatable by the responsiveness of the hydrogels to the temperature and/or pH in the environment.; In Chapter 3, poly(acrylic acid) (PAA) is grafted onto ultra-fine cellulose fibers by ceric ion initiated graft polymerization as well as by methacrylation of cellulose and the subsequent free-radical polymerization. Adsorption efficiency and activity of enzymes have been found to be affected by the graft structures of PAA. Enzymes adsorbed on these fibrous supports show much improved tolerance in exposure to organic solvent and enhanced reuse efficiency.; Chapter 4 documents the generation of hydrogel microfibers from electrospinning of the intelligent hydrophilic polymers, PNIPAAm and PAA. In comparison with the hydrophilically modified fibers, this novel material has higher water absorbency and exhibits more distinct swelling transition behaviors in response to stimuli.