Molecular dynamics simulations of double-shell composite energetic microspheres: Enhancing stability and reducing sensitivity of CL-20 through tannic acid and polymer binders

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) has significant potential for polymer bonded explosive (PBXs) formulations due to its high energy density. However, further efforts are needed to reduce mechanical sensitivity and enhance thermal stability. In this study, CL-20 as the inner energy-containing component, tannic acid (TA) as the intermediate layer, and six different binders as outermost coatings. Molecular dynamics simulations were performed on the resulting CL-20/TA/Binder double-layer core-shell structure. The results revealed that the TA/Poly(bis(azidomethyl)oxetane-co-tetrahydrofuran) (PBT) combination exhibited a higher glass transition temperature (Tg), increased rigidity, and improved mechanical strength. Employing TA as an intermediate layer between CL-20 and the binder enhanced binding energy and interfacial interactions compared to the CL-20/Binder system. In the interface layer of core-shell structure, TA and the binder could effectively reduce the trigger bond of CL-20, resulting in reduced sensitivity and improved safety. This research provides theoretical insights for the effective design of double-shell composite energetic microsphere particles.