Thermal properties of imidazolium ionic liquids

We investigated the thermal properties of several imidazolium salts using DSC and TGA/SDTA data. Many of these salts are liquids at sub-ambient temperatures. These ionic liquids form glasses at low temperatures and have minimal vapor pressure up to their thermal decomposition temperature (>400°C). Thermal decomposition is endothermic with the inorganic anions and exothermic with the organic anions investigated. Halide anions drastically reduce the thermal stability of these salts (<300°C). We have observed that aluminium catalyzes the decomposition of the salts containing the inorganic fluoride anions. The imidazolium cations are thermally more stable than the tetraalkyl ammonium cations.