Halogen-free polyisobutylene by in situ methylation of living polyisobutylene using dimethylzinc

Halogen-free polyisobutylene (PIB) was synthesized by in situ methylation o f living PIE using dimethylzinc. Quantitative methylation of living PIE was achieved within 60 min using a ratio of [(CH3)(2)Zn]/[TiCl4](0) = 1 withou t any side reactions. Under similar conditions, living PIE capped with 1,1- diphenylethylene (PIB-DPE+) yielded close to 1:1 mixture of methoxy- and me thyl-functionality. By using the ratio of [(CH3)(2)Zn]/[TiCl4](0) greater t han or equal to 3, however, quantitative methylation of PIB-DPE+ could be a chieved in 120 min without any side reactions as confirmed by spectroscopic and chromatographic analyses.