Synthesis of high molecular weight polyisobutylene with Al(C6F5)3-based initiating systems under mild conditions

We report here by using a binary initiating system containing a sterically bulky Lewis super acid Al(C6F5)3 together with cumyl chloride (CumCl), the cationic polymerization of isobutylene was realized at temperatures varying from −60 °C to 15 °C in a non-halogenated solvent to afford polymers with medium molecular weights from 0.9 × 104 to 14.8 × 104 g·mol−1. Moreover, addition of EDs (EDs = OPh2, SPh2 and NPh3) to the above system generated ternary systems, leading to obvious improvement of the catalytic performances. Among these systems, Al-CumCl-OPh2 was mostly efficient to transfer up to 20,000 equiv. IB into PIBs with high molecular weights up to 35.5 × 104 g·mol−1 at −40 °C. The activation energies (Ep) for the polymerization degree with different initiating systems were determined, suggesting that the molecular weight of PIB was strongly dependent on the polymerization temperature.