Polymerization of vinyl acetate in aqueous media. Part II. The kinetic behavior in the presence of low concentrations of added soaps

The effect of adding low concentrations of the three different types of soaps on the heterogeneous polymerization of vinyl acetate in aqueous solution, with K2S2O8 as initiator, has been studied. Neutral soaps produced no appreciable effect on the polymerization rate, whereas anionic soap increased the rate, the magnitude of the increase being affected by the length of the paraffin chain in the anion. Cationic soaps decreased the rate of polymerization in the early stages of the reaction, but in this case the length of the paraffin chain in the cation had no influence. The results have been interpreted in terms of the adsorption of the soap onto the surface of the small polymer particles, and the resultant reduction or promotion of the coalescence of these small particles.