Extemporaneous Mechanochemistry: Shockwave Induced Ultrafast Chemical Reactions Due to Intramolecular Strain Energy

TL;DR

This paper demonstrates through large-scale molecular dynamics simulations that intramolecular strain energy, induced by shockwaves, accelerates chemical reactions and alters decomposition mechanisms in energetic materials, providing insights for improved modeling.

Contribution

It provides the first direct molecular evidence linking intramolecular strain to accelerated and mechanochemically altered reactions in energetic materials.

Findings

Intramolecular strain accelerates decomposition kinetics.

Shockwave-induced strain alters reaction pathways.

Molecular dynamics reveal mechanochemical effects at the atomic level.

Abstract

Regions of energy localization referred to as hotspots are known to govern shock initiation and the run-to-detonation in energetic materials. Mounting computational evidence points to accelerated chemistry in hotspots from large intramolecular strains induced via the interactions between the shockwave and microstructure. However, definite evidence mapping intramolecular strain to accelerated or altered chemical reactions has so far been elusive. From a large-scale reactive molecular dynamics simulation of the energetic material TATB, we map molecular temperature and intramolecular strain energy prior to reaction to decomposition kinetics. Both temperature and intramolecular strain are shown to accelerate chemical kinetics. A detailed analysis of the atomistic trajectory shows that intramolecular strain can induce a mechanochemical alteration of decomposition mechanisms. The results in this paper can inform continuum-level chemistry models to account for a wide range of mechanochemical effects.