title: Super-efficient surfactant for stabilizing water-in-carbon dioxide microemulsions.
abstract: The fluorinated double-tailed glutarate anionic surfactant, sodium 1,5-bis[(1H,1H,2H,2H-perfluorodecyl)oxy]-1,5-dioxopentane-2-sulfonate (8FG(EO)(2)), was found to stabilize water-in-supercritical CO(2) microemulsions with high water-to-surfactant molar ratios (W(0)). Studies were carried out here to obtain detailed information on the phase stability and nanostructure of the microemulsions by using a high-pressure UV-vis dye probe and small-angle neutron scattering (SANS) measurements. The UV-vis spectra, with methyl orange as a reporter dye, indicated a maximum attainable W(0) of 60 at 45 and 75 °C, and SANS profiles indicated regular droplet swelling with a linear relationship between the water core nanodroplet radius and W(0). This represents the highest water solubilization reported to date for any water-in-CO(2) microemulsion. Further analysis of the SANS data indicated critical packing parameters for 8FG(EO)(2) at the microemulsion interface >1.34, representing approximately 1.1 times the value for common aerosol-OT in water-in-heptane microemulsions under equivalent conditions.
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan. sagisaka@cc.hirosaki-u.ac.jp
authors.forename: Masanobu
authors.initials: M
authors.lastname: Sagisaka
authors.forename: Shuho
authors.initials: S
authors.lastname: Iwama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshizawa
authors.forename: Azmi
authors.initials: A
authors.lastname: Mohamed
authors.forename: Stephen
authors.initials: S
authors.lastname: Cummings
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Rogers
authors.forename: Richard K
authors.initials: RK
authors.lastname: Heenan
authors.forename: Julian
authors.initials: J
authors.lastname: Eastoe