Benzyl thiophene-2-carbodithioate and 2-methyl-2-(4-methylcyclohex-3-enyl)propyl thiophene-2-carbodithioate were synthesized. The reversible addition-fragmentation chain transfer polymerizations of styrene with benzyl thiophene-2-carbodithioate and 2-methyl-2-(4-methylcyclohex-3-enyl)propyl thiophene-2-carbodithioate as chain-transfer agents and with 2,2-azobisisobutyronitrile as an initiator were carried out. The polymerization kinetics were investigated. An ab initio calculation method was used to explore the differences between benzyl thiophene2-carbodithioate and benzyl benzodithinate. The structure of the obtained polymers was characterized with H-1-NMR. Chain-extension experiments of the obtained polymer with styrene were carried out. (c) 2007 Wiley Periodicals, Inc.