On the Reaction Characteristics of Miniemulsion Polymerization with Aqueous Phase Initiation - Experiments and Modeling

Miniemulsions, consisting of submicron droplets of very hydrophobic lauryl methacrylate or 4‐tert‐butyl styrene, are successfully polymerized using water‐soluble sodium persulfate. Monitoring the calorimetric profile as well as the droplet and particle size distribution with conversion manifests a process of monomer redistribution, droplet disappearance, and narrowing of the particle size distribution. The observed reaction characteristics could be modeled adequately, using thermodynamic principles. The results of the work presented do not only have predicting value, but also enfeeble the idea of a one‐to‐one translation of monomer droplets into polymer particles in miniemulsion polymerization. Monomer redistribution, droplet disappearance, and narrowing of the particle size distribution have been observed for miniemulsion polymerizations of monomers with different water solubilities, initiated by water‐soluble sodium persulfate. These phenomena are mechanistically explained using thermodynamic principles, clearly displaying that a one‐to‐one copy of monomer droplets into polymer particles is not an intrinsic property of miniemulsion polymerization.