Journal of Polymer Science Part A: Polymer Chemistry, Vol.37, No.14, 2429-2437, 1999
Preparation of micron-size polystyrene particles in supercritical carbon dioxide
The dispersion polymerization of styrene in supercritical CO, utilizing poly(1,1-dihydroperfluorooctyl acrylate) (p-FOA) as a polymeric stabilizer was investigated as well as poly(1,1-dihydroperfluorooctyl methacrylate) (p-FOMA). The resulting high yield (>85%) of spherical and relatively uniform polystyrene (PS) particles with micron-size range (2.9-9.6 mu m) was formed for 40 h at 370 bar using various amounts of p-FOA and p-FOMA as a stabilizer with good stability until the end of the reaction. The particle diameter was shown to be dependent on the weight percent of added stabilizer. Previously, we reported that p-FOA was not effective for the dispersion polymerization of styrene as a stabilizer. Here, we find that p-FOA can indeed be an effective stabilizer for the dispersion polymerization of styrene in supercritical CO2, but the pressure necessary to achieve good stability is higher than pressure used by us previously. This study suggests the possibility that fluorinated acrylic homopolymers are effective for the dispersion polymerization of various kinds of monomers as a stabilizer.
Keywords:supercritical CO2;dispersion polymerization;styrene;polymer particles;stabilizer;cloud point