Ionic polymerization under electric field. II. Radiation‐induced polymerization of styrene

Radiation‐induced polymerization of styrene was carried out at −78°C. in methylene chloride under strong electric field. The rate of polymerization was enhanced in the presence of electric field whereas the degree of polymerization remained virtually unaffected. It was pointed out that the enhancement of the rate could be accounted for by the increase of ion yield due to the field, assuming free ion mechanism. The electric conductivity of the polymerizing solution was suggested to be mainly due to an electrolyte produced by solvent radiolysis. Using ethylbenzene and toluene instead of methylene chloride, which are believed to be fairly stable to the radiation, the conductivity was measured. From the measurements, the average life time of ions supposedly from styrene molecule was estimated to be 10−1∼10−2 sec., which are believed to be responsible for the radiation‐induced polymerization.