title: Dual stimuli-responsive N-phthaloylchitosan-graft-(poly(N-isopropylacrylamide)-block-poly(acrylic acid)) copolymer prepared via RAFT polymerization.
abstract: In order to develop stimuli-responsive hydrogel, chitosan graft copolymer with chitosan back-bone and poly(N-isopropylacrylamide)-block-poly(acrylic acid) (PNIPAAm-b-PAA) branch chains was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization in DMF. The chain transfer agent was obtained by modification of chitosan with 3-benzylsulfanyl thiocarbonylsulfanyl propionic acid (BPATT) with 68% the degree of substitute. The graft polymerizations possessed controlled/living characteristics. The behavior of the graft copolymer in aqueous solution was investigated by dynamic light scattering, transmission electron microscopy, and UV-visible spectrophotometer. N-Phthaloylchitosan-graft-(poly(N-isopropylacrylamide)-block-poly(acrylic acid)) copolymer (N-phthaloylchitosan-g-(PNIPAAm-b-PAA)) could assemble to micelles in aqueous solution in range of 200-300 nm with narrow size distribution, and the hydrodynamic diameter could be controlled dependent on length of branch chains and temperature. The LCST values of micelle could be modulated from 34 to 40 °C by controlling the constitution of branch chains, pH, and concentration.
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.forename: Zhengke
authors.initials: Z
authors.lastname: Wang
authors.forename: Youliang
authors.initials: Y
authors.lastname: Li
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Jiang
authors.forename: Qiaoling
authors.initials: Q
authors.lastname: Hu
authors.forename: Minying
authors.initials: M
authors.lastname: Liu
authors.forename: Qingxiang
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry; D000180:Acrylic Resins / Q000138:chemical synthesis / Q000737:chemistry; D002686:Chitin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000138:chemical synthesis / Q000737:chemistry; D008027:Light; D008823:Micelles; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D013696:Temperature
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D008823:Micelles; C483239:N-phthaloylchitosan; D011108:Polymers; D002686:Chitin; C052970:poly-N-isopropylacrylamide; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate