Portal de Periódicos da CAPES

Living Carbocationic Polymerization of Isobutylene Using Blocked Dicumyl Chloride or Tricumyl Chloride/TiCI 4 Pyridine Initiating System

1992; Taylor & Francis; Volume: 29; Issue: 11 Linguagem: Inglês

10.1080/10601329208054138

1520-5738

Robson F. Storey, Youngkwan Lee,

Carbon dioxide utilization in catalysis

Abstract Living polymerization of isobutylene was achieved using an initiation system based on either 1,3-di(1-chloro-l-methylethyl)-5-tert-butylbenzene (tert-butyl-dicumyl chloride) or 1,3,5-tris(l-chloro-l-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 ≈ 1.1) and quantitative initiation efficiency (Ieff < 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.