Synthesis of bisimidazolium–ionic liquids: Characterization, thermal stability and application to bentonite intercalation

Abstract

In this study, a convenient method was developed for the synthesis of bisimidazolium salts and bisimidazolium-ionic liquids. The products were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), mass spectroscopy, elemental analysis and thermogravimetric analyses (TGA). The effect of the counter ion, alkyl chain length and structural isomerism on the thermal stability of the bisimidazolium salts was investigated. Ionic liquid-treated bentonite clays were prepared by ion exchange of the bisimidazolium cations with Na-bentonite. These new organoclays were characterized by X-ray diffraction (XRD), FTIR and TGA. The results show that the ionic liquid-intercalated bentonites have greater thermal stability (450-470 • C) compared with the bisimidazolium-or the diphosphonium-exchanged bentonites.

Thermal Stability of Ionic Liquids: Current Status and Prospects for Future Development

“…Anions play a major role in determining thermal stability, which has been confirmed in many studies [46,58,59]. For 1,2,4-triazolium ILs, the stability increases in the order [NTf2] Table 10).…”

“…The thermal stability of ILs is mainly determined by the structure of anions and cations, and anions usually play a major role [46,58,59]. However, more studies are focused on the modification of cations, including alkyl chain length, functional groups, and alkyl substituents to improve the thermal stability of ILs [60,61].…”

Thermal Stability of Protic Ionic Liquids

“…However, their thermal stability has been shown to vary greatly depending on heating rate, , presence of impurities, , and environmental factors such as atmosphere and synthesis temperature . The thermal stability of ILs depends on the combinations of ions present, − noting that chemical decomposition of the cation typically occurs first. Thermal properties are commonly assessed through the utilization of differential scanning calorimetry (DSC) to analyze thermal transitions and thermogravimetric analysis (TGA) to determine decomposition temperature via mass loss.…”

Biocomposites based on bentonite and lecithin: An experimental approach supported by molecular dynamics

“…In previous studies, quaternary ammonium salts were widely applied in montmorillonite modification and exhibit superior performances in oil-based drilling fluid (Zhuang et al, 2015); (Zhou et al, 2016); (Zhang et al, 2017); (Makhoukhi et al, 2013;Makhoukhi et al, 2016;Xie et al, 2002), notably a better dispersibilty.…”