Radiochemical investigation of low unsaturations in polystyrene—I. Polystyrene prepared by a cationic mechanism

Abstract

Double bonds present in polystyrene prepared using stannic chloride in methylene chloride at −78° have been estimated by reaction with radiochlorine. It is found that unsaturation is exclusively terminal and every chain contains one unsaturated end. This shows that the mode of termination in the polymerization involves proton expulsion, and not, under these conditions, the formation of phenylindane-type end structures. The fall in molecular weight on degradation under vacuum of polystyrene prepared by the cationic mechanism is shown to be similar to that previously reported for polymer prepared by a free radical mechanism, despite the total absence of main chain unsaturation. It appears, therefore, that the double bonds present in the main chain of polystyrene prepared by the free radical mechanism cannot be associated with weak links, as was previously suggested.