Cationic polymerization of isobutylene with H2O/TiCl4 initiating system in the presence of electron pair donors

Abstract Cationic polymerization of isobutylene (IB) in a mixture of methylene dichloride (CH 2 Cl 2 ) and n -hexane ( n -Hex) was conducted by using H 2 O as initiator, TiCl 4 as co-initiator in the presence of strong external electron pair donor (ED), such as pyridine (Py), dimethylacetamide (DMA) or triethylamine (TEA). The effects of ED concentration, TiCl 4 concentration, solvent polarity, polymerization temperature ( T ) and time on IB polymerization, molecular weight (MW) and molecular weight distribution (MWD, M w / M n ) of polyisobutylene (PIB) products were investigated. The relative amount of polymer formed via uncontrolled initiation by conventional active species (I) decreased with increasing the solvent polarity, TiCl 4 concentration and ED concentration in the polymerization. The desirable polymerization of IB with apparent absence of chain transfer reactions could be obtained by H 2 O/TiCl 4 initiating system in the presence of ED under the appropriate reaction conditions. The external electron pair donors and TiCl 4 did specially play important and effective roles on polymerization.