LIVING CATIONIC POLYMERIZATION OF BENZYL VINYL ETHER AND ITS BLOCK-COPOLYMERS WITH NARROW MOLECULAR-WEIGHT DISTRIBUTION

The living cationic polymerization of benzyl vinyl ether (BnVE) was achieved by the CH3CH(OiBu)OCOCH3(1)/EtAlCl2 initiating system in the presence of added bases. The effects of polymerization temperature and solvent were investigated in detail. Polymerizations in the presence of ethyl acetate at below 0-degree-C in a non-polar solvent (toluene or CCl4) gave living polymers with a narrow molecular weight distribution (MWD) (MBAR(w)/MBAR(n) approximately 1.1). The MBAR(n) of the polymers increased in proportion to monomer conversion. The obtained living polymer was rich in isotacticity (approximately 80%) by H-1 NMR analysis. Fast living polymerization also occurred in the presence of methyl chloroacetate to synthesize higher molecular weight poly(BnVE) than MBAR(n) = 10(5). Block copolymers were prepared by the sequential living polymerization of BnVE and isobutyl vinyl ether. Debenzylation of poly(BnVE) and its block copolymers was achieved by two methods [(A)HBr in toluene and (B) Na in liq. NH3] to give PVA and its block copolymers with a narrow MWD.