Bisulfite-initiated vinyl polymerization in aqueous media

Abstract

Bisulfite initiates aqueous polymerization of certain vinyl monomers such as methyl methacrylate, ethyl methacrylate, methacrylic acid and styrene but it fails in case of acrylonitrile, vinyl acetate, methylacrylate, and acrylic acid under identical conditions. The mechanism of initiation has been discussed. Catalyst exponent of this initiator with respect to methyl methacrylate is near about 0.5. Quantitative determination of endgroup by dye techniques of the polymers obtained show that about 2 sulfonate (-SO₃H) endgroups are present per chain in almost all cases. No sulphate endgroup (-OSO₃H) is ever found. In case of very low initiator concentration ( < 0.005 mole/1.), some hydroxyl endgroups are also found in general but the total (sulfonate and hydroxyl combined) amounts to about 2 per polymer chain.