title: Shape Modification of Water-in-CO2 Microemulsion Droplets through Mixing of Hydrocarbon and Fluorocarbon Amphiphiles.
abstract: An oxygen-rich hydrocarbon (HC) amphiphile has been developed as an additive for supercritical CO2 (scCO2). The effects of this custom-designed amphiphile have been studied in water-in-CO2 (w/c) microemulsions stabilized by analogous fluorocarbon (FC) surfactants, nFG(EO)2, which are known to form spherical w/c microemulsion droplets. By applying contrast-variation small-angle neutron scattering (CV-SANS), evidence has been obtained for anisotropic structures in the mixed systems. The shape transition is attributed to the hydrocarbon additive, which modifies the curvature of the mixed surfactant films. This can be considered as a potential method to enhance physicochemical properties of scCO2 through elongation of w/c microemulsion droplets. More importantly, by studying self-assembly in these mixed systems, fundamental understanding can be developed on the packing of HC and FC amphiphiles at water/CO2 interfaces. This provides guidelines for the design of fluorine-free CO2 active surfactants, and therefore, practical industrial scale applications of scCO2 could be achieved.
authors.affiliation: School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom.
authors.forename: Ci
authors.initials: C
authors.lastname: Yan
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Sagisaka
authors.affiliation: Rutherford Appleton Laboratory, ISIS Facility, Chilton, Oxfordshire OX11 0QX, United Kingdom.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Rogers
authors.affiliation: School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom.
authors.forename: Gavin
authors.initials: G
authors.lastname: Hazell
authors.affiliation: School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom.
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Peach
authors.affiliation: School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom.
authors.forename: Julian
authors.initials: J
authors.lastname: Eastoe