Anisotropic initial reaction mechanism and sensitivity characterization of the host–guest structure CL-20/H2O2 under shock loading

Abstract

Molecular-level interaction control and host–guest strategies are widely employed to design safer, high-performance energetic materials. This paper explores the anisotropic physicochemical response of the CL-20/H₂O₂ host–guest structure under impact along the (1 0 0), (0 1 0), and (0 0 1) crystallographic directions using reactive molecular dynamics simulations combined with the multiscale shock technique. The embedding of H₂O₂ in the CL-20 crystal cavity introduces pronounced anisotropy, driven by molecular packing differences across orientations. Elastic property analysis indicates that CL-20/H₂O₂ is more deformable, with a higher Poisson's ratio compared to anhydrous α-CL-20, but retains a brittle nature. This brittleness, combined with localized strain under shock, contributes to shear band formation, energy concentration, and hotspot generation, increasing sensitivity risks. Mechanochemically, initial decomposition is driven by N–NO₂ bond homolysis and C–N bond breakage, leading to cage structure collapse. The inclusion of H₂O₂ strengthens molecular interactions and enhances energy localization, amplifying anisotropic decomposition pathways. This study highlights the critical role of host–guest interactions in governing anisotropic decomposition and sensitivity in energetic materials, offering valuable insights for designing safer and more stable energetic materials with optimized performance.