Water-in-CO2 microemulsions with a simple fluorosurfactant

The phase behavior of supercritical CO2/ClCF2CF2CF2CF2CF2CF2OCF2CF2SO3K (F-53B)/alcohols/water/was studied in detail using a high-pressure variable-volume view cell. The results showed that F-53B could form reverse microemulsions in the presence of water and alcohols from ethanol to n-octyl alcohol. A significant amount of water could be solubilized at easily accessible conditions. The efficiency of the alcohols to enhance formation of the microemulsions was in the order: n-pentanol ≈ n-butanol > n-hexanol > n-propanol ≈ n-heptanol > octyl alcohol > ethanol. The solvatochromic probe studies further proved the existence of water domains in the supercritical CO2-based microemulsions. The microemulsions may have potential applications because the surfactant is relatively cheap and simple in structure, and the reverse microemulsions can be formed at mild conditions.