New CO2-philic hydrocarbon molecules were synthesized by reversible addition fragmentation chain-transfer polymerization. These poly(vinyl alkylates) show the highest solubility in supercritical CO2 Of any hydrocarbon reported to date. By utilizing the anchoring ability of the thiocarbonylthio end group, the dispersion polymerization of N-vinyl pyrrolidone was successfully achieved in scCO(2) leading to high yields of well-defined spherical polymer particles.