Abstract: | A series of new reversible addition–fragmentation chain transfer (RAFT) agents with cyanobenzyl R groups were synthesized. In comparison with other dithioester RAFT agents, these new RAFT agents were odorless or low‐odor, and this made them much easier to handle. The kinetics of methyl methacrylate radical polymerizations mediated by these RAFT agents were investigated. The polymerizations proceeded in a controlled way, the first‐order kinetics evolved in a linear fashion with time, the molecular weights increased linearly with the conversions, and the polydispersities were very narrow (~1.1). A poly[(methyl methacrylate)‐block‐polystyrene] block copolymer was prepared (number‐average molecular weight = 42,600, polydispersity index = 1.21) from a poly(methyl methacrylate) macro‐RAFT agent. These new RAFT agents also showed excellent control over the radical polymerization of styrenics and acrylates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1535–1543, 2005 |