Effect of Pickering stabilization on radical entry in emulsion polymerization

Abstract

The production of latexes stabilized by solid particles, so‐called Pickering stabilizers, has attracted considerable attention due to its benefits, including the enhanced mechanical properties of the polymer films. Clays for instance were found to enhance particle stabilization in emulsion polymerization, in a comparable way to conventional surfactants. Their concentration thus determines the polymer particles size and number, and consequently the reaction rate. In this work, we investigate the impact of the presence of such rigid and big platelets at the polymer particle's surface on radical exchange between the aqueous phase and the polymer particles. It was found for the system underhand that the average number of radicals per particle ( truen¯) was independent of the stabilizer layer. Therefore, a radical capture model independent of the clay concentration could be used to simulate reactions involving different clay concentrations and predict the evolution of the monomer conversion, particle size, and truen¯. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2612–2624, 2018

Modeling Polystyrene Homogeneous‐Coagulative Nucleation in Pickering Emulsion Polymerization

“…Other parts of the model required to predict different reactions and concentrations in the different phases can be found in the Supporting Information. [ 32,48 ] Note that these parts of the model are similar to conventional modeling of emulsion polymerization.…”

“…In a previous work, the effect of the layer of inorganic clay coating the polymer particles on radical capture was evaluated in seeded emulsion polymerization (where the number of particles was constant, so coagulation and nucleation were negligible). [ 32 ] The main results were the following: the pseudobulk model could be used to predict the particle size distribution since the particles were big enough (200 nm in diameter) to contain more than one radical at any given time or to make radical exit become negligible; Radical exit was estimated to be negligible for the considered particle size and reaction temperature (70 °C); Finally, radical capture was found to be proportional to the particle diameter and could be described by the diffusion‐controlled mechanism with an efficiency factor of radical entry of f e = 0.014, independent of the clay concentration, so no hindrance of radical capture resulted from the presence of clay at the polymer particle surface.…”

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

“…[18] provide deep insights into the kinetics of soap-free emulsion polymerization using laponite clay as a stabilizer, in which they describe how the Pickering stabilizer concentration has an important effect on particle nucleation. Brunier et al [19] tted several radical capture models into Pickering Emulsion Polymerization data, where they nd a reasonable description with some model adjustments.…”