Living cationic polymerizations initiated by phosgene

Abstract

Living cationic polymerization of isobutylene and styrene was performed by using phosgene as initiator and solvent, AlCl₃ as coinitiator in homogeneous phase. Polymerization of isobutylene by using phosgene and TiCl₄ also proved to be a living process, however, initiation in this case was performed by “H₂O” impurities, and the system was heterogeneous. In case of the COCl₂/AlCl₃ initiating system, ketonic carbonyl functionality was built-in into the polymer. The living character of the process, both in case of AlCl₃, and of TiCl₄ was demonstrated by the linear increase of ¯M_n with the cumulative amount of the monomer successively added, and by the conversion and temperature jump at every monomer additon. Observations on the permanence of the color (intensive yellow with IB and deep red with St) also support that the propagating cations are long living. An explanation of the observed phenomena is suggested on the base of Pearson's theory of “hard” and “soft” acids and bases.