Reverse Micelles in Carbon Dioxide with Ionic‐Liquid Domains

Abstract

Supercritical CO2 is an attractive green solvent. [1] However, CO2 is generally a poor solvent for high-molecular-weight or hydrophilic molecules, which rules out many potential applications. An effective way to solve this problem is to create reverse micelles or microemulsions with supercritical CO2 as the continuous phase. Many studies have been carried out on water-in-CO2 microemulsions and reverse micelles in supercritical CO2 with water domains. [2] Researchers have also investigated the applications of water-in-CO2 microemulsions, for example, for the extraction of biomolecules and metal ions, for the preparation of nanoparticles, and as media for chemical reactions. Room-temperature ionic liquids, which are organic salts with melting points below 100 8C, have attracted much attention. They can dissolve many organic and inorganic substances, and their properties are tunable to satisfy the requirements of a variety of tasks. Many ionic liquids can be considered as cleaner solvents than standard solvents because they are nonvolatile and often nontoxic or low toxic. Ionic liquids have potential applications in a range of areas, such as separations, chemical reactions, and materials synthesis. It was reported that ionic liquids could dissolve supercritical CO2, whereas the solubility of ionic liquids in supercritical CO2 was negligible. [10]