Droplet Structure in a Water-in-CO2 Microemulsion

High-pressure small-angle neutron-scattering measurements show that a dichain hydrocarbon−fluorocarbon surfactant ((C 7 H 15 )(C 7 F 15 )CHSO 4 - Na + ) stabilizes spherical droplets, with mean water core radius around 25 Å, in a water-in-CO 2 microemulsion (temperature = 25 °C, pressure = 500 bar). At lower pressures droplet clustering is observed. Our structural work on this system builds on initial phase stability studies by Johnston et al. ( Langmuir 1994, 10, 3536).