Characterization of water/supercritical CO2 microemulsion by UV-visible spectroscopy and dynamic light scattering.

A water/supercritical CO(2) microemulsion (W/scCO(2) microE) with methyl orange (MO) and sodium bis(1H,1H,2H,2H-heptadecafluorodecyl)-2-sulfosuccinate, 8FS(EO)(2), was characterized by means of UV-visible absorption spectral and dynamic light scattering (DLS) measurements. Visual observation of the scCO(2) mixtures revealed transparent and reddish scCO(2) phases with and without separated excess water; they were identified as Winsor-II and Winsor-IV W/scCO(2) microE, respectively. The polarities of the aqueous cores in the Winsor-IV W/scCO(2) microE were examined by observing the spectral shift of the absorbance maximum of MO.