Nitroxide-mediated radical polymerization was used to synthesize poly(1, 1,2,2-tetrahydroperfluorodecyl acrylate) homopolymer. PFDA, and to tailor the synthesis Of semiflorinated polystyrene-b-PFDA block copolymer, PS-b-PFDA. The solubility of the polymers was investigated in the solvent carbon dioxide (CO2) using cloud point and light scattering techniques. The solvent quality of CO2 for PFDA homopolymer was shown to increase with CO2 pressure and this information coupled with the size of the block copolymer species indicated the fort-nation of PS-b-PFDA micelles. Residual PS homopolymer remained soluble in PS-b-PFDA micelles at low pressure and induced the formation of a second Population of larger aggregates when the solvent quality was tuned. (c) 2005 Elsevier B.V. All rights reserved.