Thermal stabilities and decomposition mechanisms under oxygen and nitrogen atmospheres for imidazolium ionic liquids with different cations

Abstract

Ionic liquids (ILs) are room temperature molten salts, have received extensive attention from the academic community due to their excellent characteristics. In the context of global warming, more and more scholars are looking forward to using ILs as a gas adsorbents, especially ILs containing bis(trifluoromethylsulfonyl)imine (Tf2N). It is well known that the thermal stabilities of ILs are affected by many factors, and the cation type is one of them. In this paper, five imidazole ILs with different functional groups on the side chains of the imidazole rings were selected as the research objects, and their anions were all Tf2N. The thermal decomposition characteristics and thermal effects of the selected samples were determined by thermal gravimetric analyzer (TGA) and differential scanning calorimetry (DSC). The experimental data showed that the most stable ionic liquid was that with the simplest side chain, and the more complex the side chain was, the lower the thermal stability of the sample. In addition, some of their decomposition products were studied with thermogravimetric analyzer coupled with Fourier-transform infrared spectrometry (TG–FTIR). The decomposition mechanisms of the samples did not change under different atmospheres.