A piece-wise reconstruction of some mechanistic steps in Pickering emulsion polymerization: a semicontinuous styrene montmorillonite-supported process as a case example

Abstract

Building on traditional emulsion polymerization research, which continues to yield results up to the present day, techniques have emerged to produce hybrid materials. One such technique is Pickering emulsion polymerization, with numerous industrial applications. Despite a growing interest in Pickering emulsion polymerization, the intrinsic mechanisms involved have been based mainly on the findings of classical emulsion polymerization. In this work, by relying on a minimum of assumptions and using a simple model and experimental data on conversion and particle size, we obtain information about the prevailing mechanisms. More specifically, we present four main findings based on data reported previously in the literature. First, in contrast to the three rate-of-reaction intervals reported in classical emulsion polymerization, the integro-differential method yielded only two rate-of-reaction intervals against conversion. Second, a master curve is constructed by plotting the reaction rate against overall conversion, showing a maximum of approximately 55% conversion. Third, despite having a semicontinuous process, monomer concentration inside the particles is not constant. Finally, particle density is a strong function of the Pickering agent concentration, where two fitting parameters (nucleation and coagulation) allowed an accurate description for the particle number time evolution. Both parameters showed a power-law dependence with clay concentration.