Influence of the chemical structure of dithiocarbamates with different N‐groups on the reversible addition–fragmentation chain transfer polymerization of styrene

Polymerizations of styrene with azobisisobutyronitrile initiation or thermal initiation have been performed in the presence of dithiocarbamates with different N‐groups, that is, benzyl 4,5‐diphenyl‐1H‐imidazole‐1‐carbodithioate (2a), benzyl 1H‐1,2,4‐triazole‐1‐carbodithioate (2b), benzyl indole‐1‐carbodithioate (2c), benzyl 2‐phenyl‐indole‐1‐carbodithioate (2d), benzyl phenothiazine‐10‐carbodithioate (2e), benzyl 9H‐carbazole‐9‐carbodithioate (2f), and benzyl dibenzo[b,f]azepine‐5‐carbodithioate (2g). The results show that the structure of the N‐group of dithiocarbamates has significant effects on the activity of dithiocarbamates for the polymerization of styrene. 2a, 2b, 2c, 2d, and 2f are effective reversible addition–fragmentation chain transfer (RAFT) agents for the RAFT polymerization of styrene, and the polymerizations have good living characteristics. However, in the cases of 2e and 2g, the obtained polymers have uncontrolled molecular weights and broad molecular weight distributions. The polymerization rate is markedly influenced by the conjugation structure of the N‐group of the dithiocarbamate, and the polymerization rate of 2b is greater than that of 2a. For 2b, the rate of polymerization seems independent of the RAFT agent concentration. However, a significant retardation in the rate of polymerization can be observed in the case of 2c. 2d is more effective than 2c, and the substitution group of phenyl on this dithiocarbamate has obvious effects on the effectiveness of the controlled polymerization of styrene. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4849–4856, 2005