Investigating molecular factors that affect thermal stability of energetic materials

The mechanisms and molecular properties that affect the thermal stability of energetic materials (EM) have not been clearly identified in the literature. Current theories suggest that the main factor governing a thermally stable material is dependent on the strength of the weakest bond (i.e., also known as the trigger linkage) in the molecule. Previous works have shown that some correlation exists between the bond dissociation energy (BDE) of the weakest bond in a material with its experimental decomposition temperature. However, our calculations of BDEs show a more complex relationship between these two values. To understand this further, we built on a previous database collected by Wespiser and Mathieu [Propellants Explos. Pyrotech. 2023, 48 (4)] that reported experimental decomposition temperatures for around 670 EMs. We developed a highthroughput computational workflow to calculate BDEs and effective kinetic parameters for molecules reported in this database. We further used interpretable machine learning models to predict thermal stability of EMs and identify factors that affect their thermal stability.

The future goal of this work is to correlate experimental thermal decomposition data with computational data to create a uniform method that can be used to create a large database of thermal properties for EMs. This database will support the development of a generative AI framework that will enable autonomous inverse design of EMs with desired thermal stability and performance properties.