Jianling Zhang and co-workers, Chinese Academy of Sciences, have created a CO2-in-ionic liquid (IL) microemulsion. An IL/surfactant mixture was saturated with increasing amounts of CO2. At low CO2 pressures, the surfactant formed dry micelles dispersed in the IL (see picture, a). As the pressure exceeded the saturated vapor pressure of CO2, liquefied CO2 entered into the micellar cores to form CO2 domains. This led to first CO2-bound micelles (b), and then CO2-swollen micelles (c).
The CO2-swollen micelles are tunable as the micellar size can be easily adjusted by the pressure of CO2. The continuous phase — the ionic liquid — also has the potential to be adjusted due to the tunable and designable nature of ILs that aries from the multiple anion and cation combinations that are possible.
This novel kind of microemulsion has potential applications in various fields, such as materials synthesis, chemical reactions, and extraction.
Images: © Wiley-VCH