Living Carbocationic Polymerization of Isobutylene with Blocked Bifunctional Initiators in the Presence of Di-tert-butylpyridine as a Proton Trap

Abstract

Abstract The polymerization of isobutylene (IB) has been studied using 5-tert-butyl-1,3-dicumyl-chloride, 5-tert-butyl-1,3-dicumyl-methyl ether, and 5-tert-butyl-1,3-dicumyl-acetate initiators in the absence and presence of 2,6-di-tert-butylpyridine (DTBP) as a proton trap. It is demonstrated that living polymerization can be achieved in the IB/initiator/TiCl4/methylchloride-n-hexane (40:60 v:v)/DTBP/-80°C system, and that polymers with close to a Poisson molecular weight distribution can be obtained in the presence of a proton trap in concentrations only slightly higher than the concentration of protic impurities in the system. The polymerization rate is a first-order function of the monomer concentration and is not affected by the excess amount of DTBP added, which indicates that the living nature of the polymerization is not due to carbocation stabilization.