Mechanism of alternating copolymerization of sulphur dioxide with donor monomers

Abstract A study was made of copolymerization of dimethylbutadiene and vinyl acetate with sulphur diozide, in order to examine the mechanism of formation of alternating copolymers, which remains debatable up to the present time. Polymerization was carried out by slowly heating a frozen glassy monomer mixture exposed to γ and UV radiation at −196°. The temperature ranges of post-polymerization taking place under these conditions were determined colorimetrically. A study was also made of low temperature post-polymerization of these systems in the presence of quinones—inhibitors of radical reactions. Copolymer yield and the overall thermal effect of copolymerization decreases with an increase in inhibitor content in the initial mixture. A signal in EPR spectra of samples during softening at given temperatures in interpreted as a signal corresponding to the product of addition of a quinone molecule to an active radical. It is concluded from these results that radical copolymerization takes place in these systems. It was shown that copolymerization of SO 2 and dimethylbutadiene and, apparently, SO 2 and vinyl acetate takes place by a mechanism of addition of binary monomer complexes to the end of a growing chain.