Phase transition diagrams of ionic liquids with liquid/gas phase boundaries

Abstract Although the solid/liquid, liquid/liquid, and solid/solid transition behaviors of ionic liquids (ILs) have been extensively studied, reports on their liquid-to-gas phase transition dynamics are scarce, due to their low volatility at ambient pressure. Here, sets of evaporation coefficients determined in vacuo and thermogravimetry curves recorded under reduced pressure were used to construct the saturation vapor pressure curves of a series of ILs. The phase transitions of these ILs are visualized as phase diagrams containing liquid/gas phase boundaries. These diagrams enable the estimation of the vapor pressure and boiling point of the IL at a specific temperature and pressure, respectively.