LIVING CATIONIC POLYMERIZATION OF ISOBUTYL VINYL ETHER BY THE CARBOXYL GROUP OF THE CARBON-BLACK ZINC-CHLORIDE INITIATING SYSTEM

The effect of zinc chloride (ZnCl2) on the cationic polymerization of isobutyl vinyl ether (IBVE) initiated by carboxyl groups on a carbon b lack surface was investigated. Although the polymerization of IBVE was initiated by carboxyl groups on the surface, the rate of polymerizati on was small and the molecular weight distribution (MWD) of polyIBVE w as very broad. The rate of the polymerization was found to be drastica lly increased, and 100% monomer conversion was achieved in a short tim e by the addition of ZnCl2. The number-average molecular weights (M(n) ) of the polyIBVE were directly proportional to monomer conversion in the polymerization initiated by the carbon black/ZnCl2 system. By addi tion of the monomer at the end of the first-stage polymerization, the added monomer was smoothly polymerized at the same rate as in the firs t stage. The M(n) of the polymer was in excellent agreement with the c alculated value, assuming that polyIBVE chain forms per unit carboxyl group on the surface and MWD was narrow (M(w)/M(n) = 1.2 similar to 1. 3). Based on the results, it is concluded that carbon black/ZnCl2 syst em has an ability to initiate the living cationic polymerization of IB VE. Furthermore, it was found that polyIBVE was grafted onto the carbo n black surface after the quenching of the living polymer with methano l. (C) 1995 John Wiley and Sons, Inc.