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 degrees 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 degrees 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. (C) 2000 Elsevier Science B.V. All rights reserved.