Terpolymerization of sulfur dioxide and methyl acrylate with electron donor monomers

The radical terpolymerization of sulfur dioxide and methyl acrylate with 1,3-butadiene, 2-methylpropene, propene, 1-hexene, 1-octene and vinyl chloride was studied by comparing the composition of terpolymers obtained under different reaction conditions and by analysis of ¹³C NMR spectra of selected terpolymers and copolymers. In the majority of systems studied, products are formed in which the ratio of SO₂ monomeric units to vinyl monomeric units is near to unity. The content of methyl acrylate monomeric units can change over a very wide range and depends mainly on the electron-donor properties of the vinyl monomer used, feed composition and conversion. An increase of the methyl acrylate content is also observed in many systems with a rise of the reaction temperature. The results obtained are interpreted in terms of a mechanisms involving the addition of individual monomers and reversibility of steps in which carbon-sulfur bonds are formed.