Influence of guest molecules on shock-induced intrinsic reactivity and reaction pathways of CL-20 based on neuroevolution potential

Abstract

Incorporating guest molecules into energetic crystal frameworks has proven to be an effective strategy for modulating microstructure and reaction mechanism. In this study, the regulatory mechanisms of guest molecules on the shock-induced intrinsic reactivity and reaction pathways of CL-20 were systematically investigated based on the neuroevolution potential. The results indicate that NCCH3 exhibits the strongest reaction-promoting effect, driving the system into a violent reaction stage rapidly. However, due to its low oxygen balance, both the detonation pressure and velocity are significantly reduced. In contrast, N2O and CO2 behave as weakly reactive, endothermic buffering guests at early stages, which delay the decomposition of CL-20 and enhance its detonation pressure. The temperature rise and detonation performance of CL-20/H2O2 are close to those of α-CL-20, while showing a certain inhibitory effect on the initial temperature increase. Reaction pathway analysis reveals that high pressure can activate additional pathways, including H abstraction, O migration, and NO2 abstraction, thereby promoting parallel reactions and radical capture. H2O and H2O2 promote radical reaction chains through endothermic processes and the release of OH/H radicals, with H2O2 exhibiting faster onset and higher intensity. CO2 and N2O primarily suppress decomposition by diluting active species and through reversible reorganization reactions, with N2O showing a more pronounced retardation effect. NCCH3 strongly promotes early stage decomposition by engaging in multiple reaction pathways, but the overall reaction proceeds incompletely at later stages. The polarity and size of guest molecules can modify the initial crystal structure, while their radical-generating capability and chemical reactivity determine how they participate in reactions, thereby jointly influencing the intrinsic reactivity and decomposition pathways of host-guest crystals.