This proposal focuses on a new approach to the formation of rod-like micelles in supercritical CO2 (scCO2). Recent successful high-pressure SANS (HP-SANS) results have shown for the first time that fluorinated surfactants can be used as viscosity modifiers for CO2. Now, very promising quaternary alkylammonium R4N+counter-ion surfactants have also been identified to induce a sphere-to-rod like micelles. This is the first time that R4N+ ions have been incorporated into CO2-philic surfactants including TC14 and AOT4. The combination of custom-made surfactants and the use of mixed-solvents represent new exciting approaches; these proposed HP-SANS experiments are essential to investigate the new R4N+ surfactants as scCO2 viscosity modifiers.