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Keywords:

  • AB block copolymer;
  • Friedel-Crafts self-alkylation;
  • polyisobutylene;
  • polystyrene;
  • quasi-living carbocationic polymerization;
  • star polymers

Abstract

Thumbnail image of graphical abstract

Friedel–Crafts self-grafting of polystyrene (PSt) under quasiliving carbocationic polymerization was utilized to develop a new rapid one-pot method for the preparation of star-shaped polyisobutylene (PIB). First, the polymerization of isobutylene led to PIB with predetermined molecular weight (equation image = 2 000) and narrow molecular weight distribution (equation image = 1.03). Then addition of relatively small amount of styrene after isobutylene consumption yielded PIB-PSt diblocks. Multiple alkylation of the resulting PSt segments by the polystyryl cations led to hyperbranched PSt cores coupling PIB chains to form a star polymer in short reaction time (within an hour) compared to reported methods. The formation of star polymers by this self-grafting mechanism was proved by gel permeation chromatography equipped with online viscosimeter and 1H NMR spectroscopy.