The application of continuously uniform latices to kinetic studies of “ideal” emulsion polymerization

In kinetic studies of emulsion polymerization, the use of latices which are completely uniform through all stages of growth offer a marked improvement in analytic accessibility over their polydispersed counterparts. This paper first reports recent developments in the technique of generating such model systems and their utility in studying the “ideal” period in emulsion polymerization. Special precautions are necessary in the use of the slow soap addition techniques since soap starvation can sometimes lead to agitation‐controlled reaction rate, and/or latex instability. A convenient‐to‐use, single‐charge formulation for styrene was developed, based on a combination of anionic and nonionic surfactants; this formulation eliminated the mixing problem and produced stable, continuously uniform latices suitable for generalized kinetic studies. Also, data on the development of both Mv and Mv in these systems give some insight into the nature of the reaction. Current steady‐state theories and the rationale associated with them predict for the “ideal” period the generation of polymer with constant molecular weight, but a substantial increase in both Mv and Mv is observed. These results suggest that either an unsteady‐state mechanism prevails or that our knowledge of the mechanism of initiation is inadequate.