Abstract: | The effect of a chain‐transfer agent (CTA) on the kinetics and molecular weight distribution of the methyl methacrylate/butyl acrylate semicontinuous emulsion polymerization was investigated. The dodecanethiol had a slight effect on the reaction rate but significantly affected the secondary nucleation. The effect of the CTA concentration on the gel formation and the effect of the reaction conditions on the mass‐transfer limitations of the CTA are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 367–375, 2000 |