Novel fluorinated double-tail surfactant having high microemulsifying ability in water/supercritical CO2 system

In order to develop an efficient surfactant for a water-in-scCO2 microemulsion (W/scCO2 μE), we synthesized a novel double-tail anionic surfactant, sodium bis(1H,1H,2H,2H-heptadecafluorodecyl)-2-sulfoglutaconate (8FG(EO)2), and examined the phase behaviour of an 8FG(EO)2/water/CO2 mixture at pressures lower than 400 bar and several water-to-surfactant molar ratios. 8FG(EO)2 yielded a transparent single phase having a higher amount of water than that soluble in pure scCO2, i.e. a W/scCO2 μE phase. Through visual observation and UV-visible absorption spectral measurement, 8FG(EO)2 was interestingly found to microemulsify at least 52 water molecules by one surfactant at 45 °C and pressures higher than 195 bar.