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 (Td) 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 Td 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 Td 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.