Title

Living Carbocationic Polymerization of Isobutylene Using Blocked Dicumyl Chloride or Tricumyl Chloride TiCl4 Pyridine Initiating System

Document Type

Article

Publication Date

1992

Department

Polymers and High Performance Materials

Abstract

Living polymerization of isobutylene was achieved using an initiation system based on either 1,3-di(1-chloro-1-methylethyl)-5-tert-butylbenzene (tert-butyl-dicumyl chloride) or 1,3,5-tris(1-chloro-1-methylethyl)benzene (tricumyl chloride) in conjunction with TiCl4 and pyridine in hexanes/methyl chloride (60/40, v/v) cosolvents. TiCl4/pyridine was found to yield narrow molecular weight distribution (MWD almost-equal-to 1.1) and quantitative initiation efficiency (I(eff) > 90%). The living nature of the polymerization system was demonstrated by the linearity of molecular weight vs conversion plots and first-order kinetic plots up to about 90% monomer conversion. If polymerization was allowed to proceed further, a departure from first-order kinetics and a broadening of the molecular weight distribution was observed to occur. The living polymerization was investigated as a function of temperature, reaction time, and the concentration of TiCl4/pyridine. Polymerization rates were observed to increase with decreasing temperature and/or increasing concentration of TiCl4/pyridine. Number-average molecular weights of the polyisobutylenes ranged from 5,000 to 100,000 under the conditions employed.

Publication Title

Journal of Macromolecular Science: Pure and Applied Chemistry

Volume

29

Issue

11

First Page

1017

Last Page

1030