Coagulation of anionically stabilized polymer particles

The stability particles produced by emulsion polymerization and stabilized by the anionic surfactant sodium dodecyl sulfate, an electrosteric surfactant with a short ethylene oxide chain, or simply with sulfate end groups were studied by turbidity measurements. Results are compared to those of electrostatic stability models based on the Derjaguin-Landau-Verwey-Overbeek theory. The good agreement between experimental and theoretical data shows that the electrosteric surfactant could be described through electrostatic approaches and that the steric contributions could be neglected. This model was incorporated into a population balance model in order to describe the coagulation between particles in a stirred tank reactor in the absence of reaction. This model was validated with experiments in which coagulation between polymer particles was provoked by electrolyte addition. The decrease of the number of particles and the resulting monomodal particle size distribution were correctly described by the model, confirming the correct determination of coagulation rates as a function of the particle diameter and surfactant concentration.