title: Thermoresponsive chitosan/N-isopropylacrylamide copolymer through atom transfer radical polymerization.
abstract: Regioseletive copolymerization of N-isopropylacrylamide (NIPAM) onto chitosan was achieved by atom transfer radical polymerization (ATRP) by using a regioselective 3,6-di-O-bromoisobutyryl-2-N-phthaloyl chitosan as a macroinitiator. The degree of polymerization (DP) of polyNIPAM onto the chitosan derivative changed by varying the ratio between NIPAM monomer, macroinitiator, ligand, and transition metal. ATRP successfully proceeded and a DP of polyNIPAM up to 110.5 was obtained. The thermal decomposition temperature of the 3,6-di-O-bromoisobutyryl-2-N-phthaloyl chitosan was significantly improved by increasing the DP of the NIPAM component. The polyNIPAM-g-chitosan derivative showed a thermoresponsive property. Although it formed a stable suspension in water at room temperature, it caused a hydrophilic-to-hydrophobic transition at around 32°C, resulting in precipitate formation.
authors.affiliation: Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan. sifuku@chem.tottori-u.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Ifuku
authors.forename: T
authors.initials: T
authors.lastname: Miwa
authors.forename: M
authors.initials: M
authors.lastname: Morimoto
authors.forename: H
authors.initials: H
authors.lastname: Saimoto
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry
chemical_list: D000178:Acrylamides; D005609:Free Radicals; D048271:Chitosan; C067295:N-isopropylacrylamide