Living carbocationic polymerization

Summary

2,6-Dimethoxy-2,4,4,6-tetramethylheptane (TMHDiOMe) in conjunction with BCl₃ has been found to be an efficient linear bifunctional aliphatic initiator for the living carbocationic polymerization of isobutylene in CH₂Cl₂ or CH₃C1 solvents at −30°C (using both the IMA and AMI techniques) and in CH₂Cl₂ at −10°C (using AMI). The living nature of the polymerization was demonstrated by linear ¯M_n versus amount of PIB formed (W_PIB) plots starting at the origin, i.e., DP_n obeyed [IB]/ [TMHDiOMe·BCl₃]. The molecular weight distributions of polyisobutylenes (PIB) synthesized at −30°C in CH₂Cl₂ were narrower (1.3–2.0) than those synthesized at −10°C in CH₂Cl₂(1.7–1.9). Forced termination by quenching with methanol produces α, Ω- tert.-chlorine capped telechelic. PIBs.