Thermal Hazard of Ionic Liquids: Modeling Thermal Decomposition Temperatures of Imidazolium Ionic Liquids via QSPR Method

Thermal hazard, which is closely related to the potential fire risk under high temperature, has become one of the most important characteristics of various ionic liquids (ILs). This study proposed a quantitative structure-property relationship (QSPR) model to predict the thermal decomposition temperature (T_d) of imidazolium ILs from their molecular structures. Not only the descriptors for single cation and anion but also those for describing their interactions were considered to numerically represent the structure characteristics of ILs. Genetic algorithm-based multiple linear regression was used to select the most statistically effective descriptors on the T_d of imidazolium ILs. The resulted model is a multilinear equation with seven variables, including two descriptors for cations, four descriptors for anions, and one interaction descriptor. The developed model was rigorously validated using multiple strategies and further extensively compared to other previously published models. The results demonstrated the robustness, validity, and satisfactory predictivity of the proposed model. The predominant structure characteristics responsible for T_d were also identified through model interpretation. The proposed model could be reasonably expected to reliably predict the thermal hazard of novel imidazolium ILs and provide guidance for prioritizing design and manufacture of safer ILs with desired properties.