gamma-Ray initiated reversible addition-fragmentation chain transfer (RAFT) polymerizations of methyl acrylate (MA) were investigated in bulk using five different dithiocarbamate structures, 2-phenyl-benzoimidazole-1-carbodithioic acid benzyl ester (1b), 2-methyl-benzoimidazole-1-carbodithioic acid benzyl ester (1c), 2-pheny-indole-1-cardithioic acid benzyl ester (1d), 2-(carbazole-9-carbothioylsulfanyl)-2-methyl-propionic acid ester (1e), and carbazole-9-carbodithioic acid naphthalene-1-ylmethyl ester (1f), as RAFT agents. The experiment results showed that MA polymerized in a controlled way under a low irradiation dose rate, i.e., first-order kinetic plots, the experimental molecular weights increased linearly with monomer conversions. The polydispersity indices of polymers generally remained at a relatively low value (lower than 1.4). The effect of irradiation dose on the polymerization results was investigated. The obtained polymers were characterized with H-1 NMR and GPC. Chain-extension reaction was also successfully carried out using the obtained polymer as the macro-RAFT agent and styrene as the second monomer. (c) 2006 Wiley Periodicals, Inc.