INITIATION VIA HALOBORATION IN LIVING CATIONIC POLYMERIZATION .1. THE POLYMERIZATION OF ISOBUTYLENE

We have discovered that, using polar solvents in the presence of a proton trap, BCl3 alone can initiate the polymerization of isobutylene. The polymerization rate increased in the order methyl chloride, methylene chloride, 1,2-dichloroethane. Increasing the BCl3 concentration increases the rate; however the molecular weights are similar at similar conversions. Change in temperature in the studied range -25 to -60-degrees had no effect on the polymerization rate or on the molecular weights. The products are low molecular weight asymmetric telechelic polymers carrying a BCl2- head group and a tertiary chloro end group. A new initiation mechanism via haloboration is proposed to explain the apparent livingness of the polymerization and the structure of the polymers.