Xanthate‐Mediated Controlled/Living Free‐Radical Polymerization under 60 Co γ ‐Ray Irradiation: Structure Effect of O ‐Group

Summary: The free‐radical polymerizations of vinyl monomers have been studied under 60 Co γ ‐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 even 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 γ ‐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 γ ‐ray irradiation.The structures of the xanthates used here.