LIVING CARBOCATIONIC POLYMERIZATION OF ISOBUTYLENE AND SYNTHESIS OF ABA BLOCK-COPOLYMERS BY CONVENTIONAL LABORATORY TECHNIQUES

Living polymerization of isobutylene (IB) and subsequent controlled sy nthesis of ABA block copolymers, such as poly(styrene-b-isobutylene-b- styrene) (PSt-PIB-PSt) and y(p-methylstyrene-b-isobutylene-b-p-methyls tyrene) (PpMeSt-PIB-PpMeSt), have been carried out by a simple and ine xpensive conventional laboratory technique. The homo- and block copoly mers obtained by using this technique have exhibited excellent molecul ar weight control and low polydispersity indexes. The living nature of IB polymerization has been demonstrated by the incremental monomer ad dition (IMA) method with the dicumyl methyl ether (DiCumOMe)/TiCl4 ini tiating system in the presence of 2,5-di-tert-butylpyridine (DtBP) pro ton trap. PSt-PIB-PSt and PpMeSt-PIB-PpMeSt block copolymers have been synthesized by sequential monomer addition: first living difunctional polyisobutylene (PIB) midsegment was prepared by difunctional initiat or, then the second monomer was added to the charge. High blocking eff iciencies and desired block copolymer structures have been obtained.