Preparation of micron-size polystyrene particles in supercritical carbon dioxide

The dispersion polymerization of styrene in supercritical CO, utilizing pol y(1,1-dihydroperfluorooctyl acrylate) (p-FOA) as a polymeric stabilizer was investigated as well as poly(1,1-dihydroperfluorooctyl methacrylate) (p-FO MA). The resulting high yield (>85%) of spherical and relatively uniform po lystyrene (PS) particles with micron-size range (2.9-9.6 mu m) was formed f or 40 h at 370 bar using various amounts of p-FOA and p-FOMA as a stabilize r with good stability until the end of the reaction. The particle diameter was shown to be dependent on the weight percent of added stabilizer. Previo usly, we reported that p-FOA was not effective for the dispersion polymeriz ation of styrene as a stabilizer. Here, we find that p-FOA can indeed be an effective stabilizer for the dispersion polymerization of styrene in super critical CO2, but the pressure necessary to achieve good stability is highe r than pressure used by us previously. This study suggests the possibility that fluorinated acrylic homopolymers are effective for the dispersion poly merization of various kinds of monomers as a stabilizer. (C) 1999 John Wile y & Sons, Inc.