Living cationic polymerization of p-alkoxystyrenes by free ionic species

In contrast to the common view, living cationic polymerization of p-methoxy - and p-t-butoxystyrenes proceeded in polar solvents such as EtNO2/CH2Cl2 m ixtures, and involvement of free ionic growing species therein was examined . For example, the two alkoxystyrenes were polymerized with the isobutyl vi nyl ether-HCl adduct/ZnCl2 initiating system at -15 degrees C in such polar solvents as CH2Cl2 or EtNO2/CH2Cl2 [1/1 (v/v)], as well as toluene. The nu mber average molecular weight ((M) over bar)(n) of the polymers increased i n direct proportion to the monomer conversion, even after sequential monome r addition, and the molecular weight distribution (MWD) stayed very narrow throughout the reaction. In addition, the (M) over bar(n) agreed with the c alculated values, assuming that one adduct molecule generates one living po lymer chain. In these polar media the addition of a common ion salt retarde d the polymerization, indicating that dissociated ionic species are involve d in the propagating reaction. (C) 1999 John Wiley & Sons, Inc.