Photoinduced ionic polymerization. II. Cationic polymerization of α-methylstyrene in the presence of tetracyanobenzene

Abstract The dependence of the rate of polymerization on light intensity and the stereoregularity of the polymer was studied to elucidate the propagation and termination mechanisms of the photoinduced cationic polymerization of α‐methylstyrene in the presence of tetracyanobenzene in methylene chloride. The rate of polymerization was proportional to the light intensity. The polymer is highly syndiotactic, and the stereoregularity is similar to that of polymers obtained by radiation‐induced cationic polymerization. The initiation mechanism was also studied by electron spin resonance, by which the anion radical of tetracyanobenzene formed from a photoexcited complex between α‐methylstyrene and tetracyanobenzene was observed. The cation radical of α‐methylstyrene, counterpart of the anion radical, is believed to initiate the polymerization.