Macromolecular Brushes Synthesized by Grafting From Approach Based on Click Chemistry and RAFT Polymerization

Well-defined macromolecular brushes with poly (N-isopropyl acrylamide) (PNIPAM) side chains on random copolymer backbones were synthesized by grafting from approach based on click chemistry and reversible addition-fragmentation chain transfer (RAFT) polymerization. To prepare macromolecular brushes, two linear random copolymers of 2-(trimethylsilyloxy)ethyl methacrylate (HEMA-TMS) and methyl methacrylate (MMA) (poly(MMA-co-HEMA-TMS)) were synthesized by atom transfer radical polymerization and were subsequently derivated to azide-containing polymers. Novel alkyne-terminated RAFT chain transfer agent (CTA) was grafted to polymer backbones by copper-catalyzed 1,3-dipolar cycloaddition (azide-alkyne click chemistry), and macro-RAFT CTAs were obtained. PNIPAM side chains were prepared by RAFT polymerization. The macromolecular brushes have well-defined structures, controlled molecular weights, and molecular weight distributions (M-w/M-n <= 1.23). The RAFT polymerization of NIPAM exhibited pseudo-first-order kinetics and a linear molecular weight dependence on monomer conversion, and no detectable termination was observed in the polymerization. The macromolecular brushes can self-assemble into micelles in aqueous solution. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 443-453, 2010