A NEW IODINE-FREE INITIATING SYSTEM FOR THE LIVING POLYMERIZATION OF ISOBUTYL VINYL ETHER

A new iodine-free initiating system, MeCH(Oi-Bu)Cl/n-Bu4NTiCl5, was found to induce the living carbocationic polymerization (LC+Pzn) of isobutyl vinyl ether (IBuVE) at -20-degrees-C in CH2Cl2. Using this system, poly(isobutyl vinyl ether) (PIBuVE) with the theoretical molecular weights (up to ca 45,000)calculated from the initiator/monomer input and narrow molecular weight distribution (M(W)BAR/M(n)BAR < 1.1) can be readily obtained. The polymerization is first order in the monomer. The coinitiating function of n-BU4NTiCl5 may be due to a salt effect or to its Lewis acid character. An attempt for the synthesis of the polyisobutylene (PIB) - PIBuVE block copolymer has failed most likely because n-Bu4NTiCI5 is unable to activate the approximately C(CH3)2-Cl bond of the PIB termini.