3 research outputs found
Supercritical carbon dioxide:a solvent like no other
Supercritical carbon dioxide (scCO2) could be one aspect of a significant and necessary movement towards green chemistry, being a potential replacement for volatile organic compounds (VOCs). Unfortunately, carbon dioxide has a notoriously poor solubilising power and is famously difficult to handle. This review examines attempts and breakthroughs in enhancing the physicochemical properties of carbon dioxide, focusing primarily on factors that impact solubility of polar and ionic species and attempts to enhance scCO2 viscosity
Shape Modification of Water-in-CO<sub>2</sub> Microemulsion Droplets through Mixing of Hydrocarbon and Fluorocarbon Amphiphiles
An oxygen-rich hydrocarbon (HC) amphiphile
has been developed as
an additive for supercritical CO<sub>2</sub> (scCO<sub>2</sub>). The
effects of this custom-designed amphiphile have been studied in water-in-CO<sub>2</sub> (w/c) microemulsions stabilized by analogous fluorocarbon
(FC) surfactants, nFGÂ(EO)<sub>2</sub>, 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 scCO<sub>2</sub> 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/CO<sub>2</sub> interfaces.
This provides guidelines for the design of fluorine-free CO<sub>2</sub> active surfactants, and therefore, practical industrial scale applications
of scCO<sub>2</sub> could be achieved