Preparation of micron-sized copolymer particles encapsulating inorganic materials by suspension polymerization in a microfluidic device

Abstract

The synthesis of polymer particles encapsulating other materials is a very attractive research field because of its broad applications. Various industries, including agriculture, drug, environment, food, cosmetics are showing increased interests in these hybrid particle systems, because of their potential in the controlled release of chemical substances initially entrapped in the internal networks. Several synthesis methods to make polymer particles by heterogeneous polymerization such as emulsion, dispersion and suspension method are available that employ either oil-in-water or water-in-oil systems. Among these methods, suspension polymerization is particularly suited to the production of micron-sized polymer beads containing pigments, drugs and other materials because of its simplicity. Here, one of the most important and complicated factors in suspension polymerization is stability of dispersed system which is characterized by a constant behavior during the process and the uniform distribution of the dispersed phase in the continuous phase. It needs very high speed of agitation to reduce the emulsion drop size to the micron scale. Still it is difficult to get fine particles with desired surface morphology. Thus, size distribution and morphology are important issues in the preparation of polymer particles encapsulating foreign material. One way to generate droplets of uniform size and shape is to use a microfluidic device. In this study, suspension polymerization was performed to prepare micron-sized copolymer beads. Co-flowing microfluidic device was introduced to overcome limitations of conventional method to produce micron-sized monomer droplet with narrow size distribution. Stable emulsion solution was prepared using a microfluidic device and emulsion droplet diameter could be controlled by changing flow rate of continuous phase. Styrene-butyl acrylate copolymer particles encapsulating carbon black could be polymerized. The emulsion droplet dia...