Studies on the Synthesis and Properties of Energetic Ionic Liquids Based on Imidazolium Compounds

Abstract

Starting from N-methylimidazole, 1,2-dimethylimidazole and 2-chloroethanol, a series of imidazolium-based ener- getic ionic liquids were synthesized via quaternization, nitration and metathesis reactions. All the energetic ionic liquids were characterized by ultraviolet visible spectrum (UV-Vis), infrared spectrum (IR), mass spectrometry (MS), nuclear magnetic resonance (NMR) and elemental analysis. The solubility study of these ionic liquids was carried out with commonly used or- ganic solvents, which showed that the energetic ionic liquids dissolved easily in polar solvents. Moreover, the ionic liquids had good thermo-stabilities indicated by thermal gravimetric analysis (TG-DTG) and differential scanning calorimetry (DSC). TG-DTG analyses showed that N-nitrooxyethylimidazolium nitrate decomposed at about 160 ℃ and N-hydroxyethylimida- zolium ionic salts decomposed above 190 ℃. Furthermore, there was an obvious glass transition process for the energetic ionic liquids based on 1-(2-nitrooxyethyl)-3-methylimidazolium and N-hydroxyethylimidazolium during the secondary heating process of DSC, which was the unique property of ionic liquids. Their densities and standard enthalpies of formation and det- onation properties were calculated and analyzed. Keywords energetic materials; quaternary ammonium; metathesis; thermal properties; detonation properties