The novel monomer, vinyl trifluorobutyrate (VTFBu), when polymerized in a controlled fashion by RAFT/MADIX polymerization with a xanthate transfer agent, yields poly(vinyl ester)s with improved solubility in supercritical carbon dioxide. The thermodynamic parameters controlling the solubility of VTFBu/vinyl acetate statistical copolymers are discussed based on ab initio calculations, glass transition temperatures of the copolymers, and surface tension measurements. The enhanced solubility of this new class of CO 2 -philic polymer combined with its good chemical stability render it attractive for the preparation of next-generation macromolecular surfactants for the formation of water−scCO 2 emulsions. T he replacement of conventional organic solvents has been identified as a key step in reducing the environmental cost of chemical synthesis, processing, and separations. 1 Supercritical carbon dioxide (scCO 2 ) is a promising environmentally benign solvent that provides low flammability, toxicity, cost, reactivity at an accessible critical temperature, and pressure (31.1°C, 73 bar). For most compounds, however, scCO 2 is a poor solvent because of its very low dielectric constant and polarizability: only relatively nonpolar low molecular weight compounds and a few fluorinated or silicone polymers show significant solubility. This drawback can be overcome by the use of water-in-scCO 2 or scCO 2 -in-water emulsions or microemulsions, which allow high concentrations of polar, ionic, and nonpolar molecules to be solubilized within the dispersed and continuous phases. Surfactants are necessary to stabilize these emulsions. For this application, amphiphilic block copolymers are of interest as they offer better anchoring and steric stabilization at interfaces than low molar mass surfactants.While fluorinated polyacrylates, perfluoroalkylethers and polysiloxanes are the current CO 2 -philic materials of choice, 2 poly(vinyl ester)s combine moderate CO 2 -philicity with favorable price and toxicity. Low molecular weight (M n = 2060 g/mol) poly(vinyl acetate) (PVAc) is soluble at 5 wt % in CO 2 at 374 bar and 25°C. The cloud point pressure and solubility are strongly dependent on the chain length, however, which limits the usefulness of higher molecular-weight PVAc. 3,4 Different strategies have been used to enhance poly(vinyl ester) solubility, such as modification of the chain end with a CO 2 -philic fluorinated segment 4 or copolymerization of vinyl acetate (VAc) with a comonomer. In the latter strategy, incorporation of repulsive or bulky pendant groups increases CO 2 solubility by enhancing entropic contributions and decreasing polymer− polymer interactions. A large palette of comonomers are available by varying the vinyl ester group, allowing the incorporation of linear aliphatic or branched structures 5−7 and fluorinated moieties. 8−10 Thus, the cloud point pressure (P c ) of a 0.2 wt % solution of PVAc (M n = 4000 g/mol; P c = 280 bar at 40°C) falls dramatically to 222 or 177 bar for statistical copolymers containing 1...