Mechanism of emulsification and demulsification for temperature-sensitive ionic liquid microemulsion

Abstract

It is known that traditional microemulsions are thermodynamically stable mixtures which are extensively applied in many fields. However, how to control emulsification and demulsification of microemulsions more flexibly in practical applications is still a challenge. In the present study, a new type of temperature-sensitive ionic liquid (IL) microemulsion [P4444][CF3COO]/[C12mim]Br/H2O, composed of two ILs and water molecules, was designed. Compared with traditional microemulsions, this IL microemulsion was more sensitive to the small range of temperature. Thus, the reversible emulsification and demulsification process can easily be switched by using temperature as a trigger. To elucidate the demulsification mechanism of this temperature-sensitive IL microemulsion, a series of molecular simulations were performed at different temperatures. The simulation results indicate that the interaction between [CF3COO]− and H2O is the driving force of demulsification process. In addition, the effect of [P4444][CF3COO] and [C12mim]Br concentration on the microstructure of microemulsion was investigated rigorously. The results demonstrate that contents of both the [P4444][CF3COO] and [C12mim]Br have an important influence on the demulsification behavior of IL microemulsion.