Phase behavior and emulsion formation of novel fluoroether amphiphiles in carbon dioxide

The limitations of carbon dioxide as a processing fluid are primarily attributed to its insolubility of polar compounds. The development of new CO2-philic amphiphiles could resolve the solubility problem. A new series of fluoroether amphiphiles have been developed to address the solubility problem. The development of novel fluoroether amphiphiles has been completed for sorbitol ester, sulfates and sulfonates. The primary objective was to design and synthesize materials that have strong polar hydrophilic heads and highly CO2-philic tails. All of the amphiphiles are soluble in carbon dioxide at moderate pressures and have the capability of forming WI, WII and WIII type emulsions in CO2. The degree of solubility is heavily influenced by amphiphilic structure including chain length and branching. An examination of pressure effect on emulsion behavior shows that the high compressibility of carbon dioxide enables WI → WIII → WII phase transitions which are similar to those found with increased electrolyte concentrations.