EPR study of the photoinitiated polymerization of butadiene and of an isobutylene–butadiene mixture in the presence of VCl4

Abstract

AbstractThe EPR spectra of butadiene and of a mixture of butadiene and isobutylene in the presence of VCl4 in the dark and with irradiation have been studied. The effect of light on butadiene leads to the formation of the radical‐cation of butadiene, similarly to isobutylene. In the mixture of both monomers, radical cations of isobutylene and butadiene are formed under the effect of light. Even if isobutylene is present in excess in the mixture compared to butadiene, the formation of the radical‐cation of butadiene still prevails. In presence of oxygen, with both butadiene and the isobutylene–butadiene mixture, peroxy radicals were detected. Cyclic polybutadiene was the main product of the photochemically initiated polymerization of butadiene.