Xanthate-mediated controlled/living free-radical polymerization under Co-60 gamma-ray irradiation: Structure effect of O-group

摘要

The free-radical polymerizations of vinyl monomers have been studied under Co-60 gamma-ray irradiation in the presence of S-benzyl O-ethyl dithiocarbonate (X1), S-benzyl O-phenyl dithiocarbonate (X2), S-benzyl O-2-naphthyl dithiocarbonate (X3), S-benzyl O-(4-methoxyphenyl) dithiocarbonate (X4), and methyl 4-{(benzylthio)carbonothioyl oxy}benzoate (X5), respectively. The results indicate that the polymerizations of methyl acrylate (MA) reveal good living characteristics in the presence of X2, X3, X4, and X5 with O-aryl groups, which play an important role in polymerization behavior; large aryl groups lead to slow polymerization. In contrast, the polymerizations with X1 couldn't be controlled and the obtained polymers had a broad-molecular-weight distribution or were Evan cross-linked. In addition, it was observed that the polymerization of styrene with X2 was a controlled process though it was very slow, and the uncontrolled polymerization of methyl methacrylate (MMA) occurred under gamma-ray irradiation. To the best of our knowledge, this is the first report of xanthates being used as control agents in controlled/living free radical polymerization under gamma-ray irradiation.