The successful cationic dispersion polymerization of styrene in liquid carbon dioxide using amphiphilic black copolymers is reported. Vinyl ether block copolymers consisting of a CO2-philic fluorinated segment and a poly(methyl vinyl ether) anchoring segment were employed to stabilize the growing polystyrene (PS) particles. The effect of stabilization in these polymerizations on molar mass, molar mass distribution, and polymer yield was studied as a function of temperature and surfactant composition. Scanning electron microscopy confirmed the formation of PS particles ranging in size from 300 nm to 1 mu m in diameter.