Cationic and pseudocationic polymerization of aromatic olefins—III. [1a.b]: A re-investigation of the polymerization of styrene by perchloric acid in methylene dichloride

A reinvestigation of the polymerization of styrene by perchloric acid in methylene dichloride at 0° with improved techniques has shown that the polymerizations are not of first order throughout; after the first half-life, the reaction accelerates and the electrical conductivity of the reaction mixture increases concurrently. These phenomena are ascribed to the slow ionization of the propagating polystyrylperchlorate ester to much more rapidly propagating polystyryl ions present in very low concentrations, and in equilibrium with a much larger concentration of non-propagating polystyrylindanyl ions. Our observations, together with those of other authors on the bimodal DP distribution of polystyrenes formed under similar conditions, confirm that the pseudocationic polymerization propagated by the polystyryl perchlorate ester is indeed a distinct form of reaction.