Living cationic polymerization of n-butyl propenyl ether

Cationic polymerization of n-butyl propenyl ether (BuPE; CH3CH= CHOBu, cis/ trans = 64/36) was examined with the HCl-IBVE (isobutyl vinyl ether) adduct /ZnCl2 initiating system at -15 similar to -78 degrees C in nonpolar (hexan e, toluene) and polar (dichloromethane) solvents,specifically focusing on t he feasibility of its living polymerization. In contrast to alkyl vinyl eth ers, the living nature of the growing species in the BuPE polymerization wa s sensitive to polymerization temperature and solvent. For example, living cationic polymerization of IBVE can be achieved even at 0 degrees C with HC l-IBVE/ZnCl2, whereas for BuPE whose beta-methyl group may cause steric hin drance ideal living polymerization occurred only at -78 degrees C. Another interesting feature of this polymerization is that the polymerization rate in hexane is as large as in dichloromethane, much larger than in toluene. A new method in determining the ratio of the living growing ends to the deac tivated ones was developed with a devised monomer-addition experiments, in which IBVE that can be polymerized in a living fashion below 0 degrees C wa s added to the almost completely polymerized solution of BuPE. The amount o f the deactivated chain ends became small in hexane even at -40 degrees C i n contrast to other solvents. Thus hexane turned out an excellent solvent f or living cationic polymerization of BuPE. (C) 2000 John Wiley & Sons, Inc.