Reactions of bifunctional addition-fragmentation chain transfer agents for synthesis of polymer bearing unsaturated moieties at both ends

Abstract

Polymerizations of methyl methacrylate (MMA) and styrene (St) in the presence of bifunctional addition fragmentation chain transfer (AFCT) agents consisting of two α-(alkylthiomethyl)acryloyloxy groups connected by an alkylene group are presented. The moieties from the transfer agent were introduced almost quantitatively at both ends and at the middle of PMMA under appropriate conditions. It was confirmed by NMR spectroscopy that unsaturated and seven-membered cyclic end groups are formed by conventional AFCT and intramolecular cyclization of the radical from the transfer agents. However, formation of the cyclic end groups could be suppressed by structural modification of the transfer agent. PMMA bearing the unsaturated end group at one or both chain ends was employed as a precursor for branched block copolymer preparation.