title: Regioselective grafting of poly(ethylene glycol) onto chitosan and the properties of the resulting copolymers.
abstract: PEG was grafted onto chitosan regioselectively at the hydroxyl groups with phthaloylchitosan as an intermediate. After the graft reaction, the phthaloyl groups were deprotected to give chitosan-g-PEG copolymers with free amino groups. The chemical structure of the graft copolymers was confirmed by FT-IR, (1)H and (13)C NMR spectroscopy. The resulting graft copolymers showed improved thermal stability compared to the original chitosan, and showed a lower thermal transition temperature at around 185 degrees C. Chitosan-g-PEG exhibited a high affinity not only for aqueous acid but also for some organic solvents because of the presence of abundant free amino groups and PEG branches, and it exhibited higher hygroscopicity and moisture retention ability than chitosan. [structure: see text]
authors.affiliation: School of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China. lliu@sjtu.edu.cn
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Fangzhi
authors.initials: F
authors.lastname: Li
authors.forename: Yue'e
authors.initials: Y
authors.lastname: Fang
authors.forename: Shengrong
authors.initials: S
authors.lastname: Guo
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004058:Diffusion; D008422:Materials Testing; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D011092:Polyethylene Glycols; D048271:Chitosan