title: Preparation of a thermoresponsive lignin-based biomaterial through atom transfer radical polymerization.
abstract: Copolymerization of N-isopropylacrylamide (NIPAM) with technical hardwood kraft lignin (HWKL) was achieved by atom transfer radical polymerization (ATRP) using a selectively modified lignin-based macroinitiator. The degree of polymerization (DP) of polyNIPAM graft side chains was affected by varying the ratio of the DMF/water solvent system from 5:0 to 0:5, and an estimated DP(NIPAM) of >40 was obtained using a ratio of 1:4 (v/v). The thermal decomposition temperature of the lignin-g-polyNIPAM copolymers significantly increased with increasing DP(NIPAM). Likewise, the solubility of the lignin-g-polyNIPAM copolymers in water changed depending on copolymer structure. In both the water-soluble and suspended copolymers, at temperatures above 32 degrees C, the g-polyNIPAM component underwent the typical hydrophilic-to-hydrophobic transition, resulting in the precipitation of the copolymer.
authors.affiliation: Biomaterials Chemistry, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Kim
authors.forename: John F
authors.initials: JF
authors.lastname: Kadla
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000737:chemistry; D008031:Lignin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D000178:Acrylamides; D001672:Biocompatible Materials; D011108:Polymers; C076151:Kraft lignin; D008031:Lignin; C067295:N-isopropylacrylamide