Synthesis of Structured Polymer Particles by Micro Dispersive Suspension Polymerization

A novel suspension polymerization technique is presented to synthesize micron-size acrylate polymers with porous or hollow interior structure. The precipitation of polymer inside a liquid droplet is induced by controlling the solubility parameter of the liquid phase. It has been found that the morphology of the polymer particles is surprisingly complex as determined by thermodynamic phase separation, particle precipitation, phase inversion, and interfacial mass transfer. For example, multi-hollow particles, porous particles, single hollow particles, severely deformed particles, and particles with external holes can be produced by controlling the reaction conditions. Under certain reaction conditions, thick cellular membrane or shell is formed with a core that consists of micron-sized and uniform particles. The observed morphological complexity of the polymer particles suggests that a simple suspension polymerization process can be modified to synthesize a new class of polymer particles that can have a broad spectrum of applications. In this paper, we also present a mathematical model to calculate the local distribution of monomer, solvent, and polymer inside a polymerizing droplet to understand the morphological development.