The RAFT homopolymerization of St and copolymerization of St with Nsubstituted maleimides such as HPM

CPPM and BPPM

using AIBN as initiator

1-phenylethyl dithiobenzoate or cumyl dithiobenzoate as the chain transfer agent was investigated.The polymers were characterized by UV-Vis and GPC.The results suggested that both the homopolymerization and copolymerization exhibited a living behavior

and the molecular weight increased with the conversion and a narrow molecular weight distribution was achieved.For the homopolymerization

due to the unfavorable bimolecular termination of the PSt radicals

the capping efficiency of the PSt chains decreased gradually with the conversion.For the copolymerization

the charge transfer complex formation not only enhanced the reaction rate but also led to alternating sequence.The P(St-alt-BPPM) was also used as the macroinitiator for the ATRP of St to prepare comb-shaped PSt.The results implied that when NMP was used as solvent

the process proceeded in an uncontrolled fashion; on the other hand

when the reaction was carried out in St bulk

the comblike PSt had a much narrower MWD.