Mechanism of external electric field modulating thermal decomposition of diphenyl azidophosphate: thermal safety assessment targeting electrostatic hazard risk.

contextAddressing the research gap regarding electrostatically induced thermal runaway during the production, storage, and transportation of diphenyl azidophosphate (DAAP), this paper systematically reveals the regulation patterns of the initial thermal decomposition energy barrier of DAAP under external electric fields in different directions, combining thermogravimetric experiments and density functional theory (DFT) calculations. The intrinsic apparent activation energy of DAAP obtained from thermogravimetric testing (TG) and kinetic model fitting is in good agreement with the initial decomposition transition state energy barrier of the azide bond calculated by DFT, validating the reliability of the decomposition pathway and activation energy calculation results. Electric field simulation results indicate that a forward electric field parallel to the azide bond cleavage direction can significantly reduce the thermal decomposition energy barrier, while high-strength electric fields in other directions can enhance the thermal stability of DAAP through conformational steric shielding, electronic rearrangement, and other effects. The research results can provide theoretical support for setting electrostatic protection thresholds and risk classification management in DAAP-related production processes.

methodsThermal stability tests were carried out on a Mettler-Toledo TGA3 + 110LF thermogravimetric analyzer. Core kinetic parameters of DAAP, such as the apparent activation energy of thermal decomposition and the decomposition mechanism function, were acquired by fitting experimental data with kinetic models. The initial decomposition pathways and transition state energy barriers under different external electric fields were calculated via Gaussian 16 software, while structural optimization and electric field loading simulations were implemented based on density functional theory (DFT). Wave function analysis was performed using Multiwfn software, and visualizations of molecular configurations and electrostatic potential distributions were produced with VMD.