Temperature Responsive Cellulose-graft-Copolymers via Cellulose Functionalization in an Ionic Liquid and RAFT Polymerization

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• 作者：Andrea Hufendiek ; Vanessa Trouillet ; Michael A. R. Meier ; Christopher Barner-Kowollik
• 刊名：Biomacromolecules
• 出版年：2014
• 出版时间：July 14, 2014
• 年：2014
• 卷：15
• 期：7
• 页码：2563-2572
• 全文大小：505K
• ISSN：1526-4602

文摘

Well-defined cellulose-graft-polyacrylamide copolymers were synthesized in a grafting-from approach by reversible addition鈥揻ragmentation chain transfer polymerization (RAFT). A chlorine moiety (degree of substitution DS(Cl) 鈮?1.0) was introduced into the cellulose using 1-butyl-3-methylimidazolium chloride (BMIMCl) as solvent before being substituted by a trithiocarbonate moiety resulting in cellulose macro-chain transfer agents (cellulose-CTA) with DS(RAFT) of 0.26 and 0.41. Poly(N,N-diethylacrylamide) (PDEAAm) and poly(N-isopropylacrylamide) (PNIPAM) were subsequently grafted from these cellulose-CTAs and the polymerization kinetics, the molecular weight characteristics and the product composition were studied by nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and size exclusion chromatography of the polyacrylamides after cleavage from the cellulose chains. The number-average molecular weights, M_n, of the cleaved polymers ranged from 1100 to 1600 g mol^鈥? for PDEAAm (dispersity 膼 = 1.4鈥?.8) and from 1200 to 2600 g mol ^鈥? for PNIPAM (膼 = 1.7鈥?.1). The LCST behavior of the cellulose-graft-copolymers was studied via the determination of cloud point temperatures, evidencing that the thermoresponsive properties of the hybrid materials could be finely tuned between 18 and 26 掳C for PDEAAm and between 22 and 26 掳C for PNIPAM side chains.