Carbocationic Polymerization in the Presence of Sterically Hindered Bases. IX. High Efficiency Blocking of Poly(α-methylstyrene) from Linear and Radial Polyisobutylenes Carrying tert-Chlorine Termini in the Presence of Proton Traps

Abstract

Abstract Di-, tri-, and tristar block copolymers consisting of rubbery poly(isobutylene) (PIB) and glassy poly(α-methylstyrene) (PαMeSt) sequences have been synthesized with 70 to > 95% efficiency. The syntheses involved initiation of α-methylstyrene polymerization by linear or three-arm star PIB's carrying 1,2, or 3 tertiary chlorine termini in conjunction with SnCl4 coinitiator in the presence of 2,6-di-tert-butylpyridine (DtBP). Blocking efficiencies (B eff.) increased with the amount of DtBP and approached 100% under suitable conditions.