Synthesis Of Chitosan Graft Copolymers And Their Functional Self-assembly

Chitosan is a well-known abundant natural polymer with good biodegradability, biocompatibility and bioactivity. But the insolubility in common organic solvents and non-thermalplasticity of chitosan have delayed its utilization and basic research. Graft copolymerization of chitosan is more attractive to expand the applications as functional materials. In this dissertation, a few of graft copolymers based on chitosan were synthesized via new procedure with maleoylchitosan, PHCSMA, PHCSSA as intermediate, such as chitosan-g-poly (butyl acrylate), chitosan-g-poly (acrylic acid), chitosan-g-poly (vinyl alcohol), chitosan-g-poly (ethylene glycol), chitosan-g-poly (butylene glycol adipate) and chitosan-g-polycaprolactone. The structures and properties of these chitosan graft copolymers were investigated, and also some grafting mechanisms.1. Water-soluble maleoylchitosan was achieved by the reaction of maleic anhydride and chitosan. The graft copolymerization of BA onto chitosan was carried out with maleoylchitosan as intermediate and initiated by γ-irradiation.2. Phthaloylation of chitosan was achieved by the reaction of chitosan and phthalic anhydride. PHCSMA was synthesized by the reaction of PHCS and maleic anhydride. The graft copolymerization of BA onto chitosan was carried out with PHCSMA as intermediate and initiated by γ-irradiation. The graft percentage extent was dependent on the irradiation dose and the concentration of BA monomer.3. The pH-sensitive graft copolymer chitosan-g-PAA was achieved by the reaction of maleoylchitosan and acrylic acid.4. PHCSSA was obtained via the reaction between PHCS and maleic anhydride. PHCSSA has improved solubility in organic solvents, such as DMF and DMSO.5. The graft copolymers of PHCSSA-g-PVA were prepared by the esterification reaction of PVA and PHCSSA and the porous structure was obtained.6. The graft copolymers of PHCSSA-g-PEG and PHCSSA-g-PBGA were prepared by the reaction of PEG or PBGA terminated with hydroxyl groups with carboxylic groups of PHCSSA and the nanosphere was obtained. The graft reaction yielded copolymers with high grafting content.