On the mechanism of particle formation above the CMC in emulsion polymerization

Abstract

The mechanism of particle nucleation has great influence on the kinetics and the particle size distribution of polymer latexes produced in emulsion polymerization. These are key aspects for the application of these products and for the development of emerging processes, such as living/controlled free-radical polymerizations. One very popular theory publish in the 80s establishes that the new-born (primary) particles undergo limited coagulation even when the concentration of surfactant is above its critical micellar concentration. In this communication, the experiment that was the base for the formulation of such theory is reexamined and discussed to determine whether it can be considered as “typical condition”, such that the general character of their conclusions can be justified. In this context, the positive skewness of the PSD observed in that time and taken as an evidence of the coagulative nucleation is discussed as well.