Living Cationic Polymerization of p-Chloro-α-methylstyrene and Its Sequential Block Copolymerization with Isobutylene

The homopolymerization of p-chloro-α-methylstyrene (pClαMeSt) and its sequential block copolymerization with isobutylene (IB) initiated by 1,3-dimethyl-1,3-diphenyl-1-chlorobutane (DiαMeSt·HCl) in conjunction with BCl3 was investigated in methylcyclohexane/methyl chloride (60/40, v/v) at −80 °C. The homopolymers exhibited close to theoretical Mn's, and the diagnostic Mn−conversion and first-order (ln[M]0/[M]−time) plots were linear; thus, chain transfer and termination were not detected. The propagating chain end of poly(pClαMeSt) was exceptionally stable; no decomposition could be detected even after 5 h under monomer-starved conditions. According to the 1H NMR spectrum of homopoly(pClαMeSt), the polymer is 94% syndiotactic; however, the precipitated polymer exhibited only a glass transition at 198 °C. Recrystallization from methylcyclohexane−methyl ethyl ketone solvent mixture yielded a semicrystalline polymer with Tm = 229 °C. Sequential block copolymerization of pClαMeSt with IB was also carried out by the addition of IB to the solution of living poly(pClαMeSt), followed by the addition of TiCl4. By gel permeation chromatography, the crossover efficiency was ∼100%, and no homopolymer contamination was detected.