In this study, PDMS13-b-POEGMAx diblock copolymers consisting of a CO2-philic poly(dimethylsiloxane) (PDMS) block connected to a thermosensitive hydrophilic poly(oligoethylene glycol methacrylate) (POEGMA) block, were synthetized by reversible addition-fragmentation chain-transfer (RAFT) radical polymerization. Their ability to decrease the water-supercritical CO2 (scCO2) interfacial tension (g) and to stabilize water-scCO2 emulsions was investigated using an original home-made device developed in the laboratory. This device is able to control the pressure from 1 to 250 bar and the temperature from 40 to 80°C. It was implemented with 2 visualization windows, a drop tensiometer and a remote optical head for dynamic light scattering (DLS) measurements. These experiments revealed that PDMS-b-POEGMA decreased g down to 1-2 mN/m and was the most efficient at high pressure (250 bar) and low temperature (40°C) where PDMS and POEGMA blocks exhibited the highest affinity for their respective phase. The diblock copolymers were shown to stabilize water-scCO2 emulsions. Moreover, the thermosensitive behavior of the POEGMA block in water (with a lower critical solubility temperature around 65°C) resulted in the formation of temperature-responsive emulsions that could reversibly switch at 100 bar from stable at 40°C to unstable at 80°C. These results were rationalized based on the solubility of each individual block of the copolymers in water and scCO2 as a function of temperature and pressure.