Cationic polymerization of hydrocarbon monomers induced by complexes of acycl halides with lewis acidsSynthesis of block copolymers of isobutylene with α-methylstyrene

The block polymerization of isobutylene with α-methylstyrene induced by acyl initiators was investigated. Thekel/kp values (the criterion for “closeness to the living state,”), wherekel is the rate constant of proton elimination from a growing carbocation andkp is the rate constant of chain growth, were analyzed. The minimumkel/kp values are characteristic of processes occurring in the presence of PhCOCl·2AlBr3 and an equimolar mixture of MeCOBr·AlBr3 with PhCOCl·AlBr3. It was concluded that these complexes are efficient initators for the synthesis of block copolymers with a relatively narrow molecular-weight distribution and a low content of homopolymers.