Interfacial self-assembling of nano-TATB@PDA embedded football-like CL-20 co-particles with reduced sensitivity

Abstract

In this study, to effectively reduce the mechanical sensitivity of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaiso-wurtzitane (CL-20) while maintaining its high energy density, an interfacial controlled self-assembly technique was employed to prepare co-particles containing minimal amounts of nano-sized insensitive compounds. Herein, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), a commonly used insensitive energetic compound, was employed. Through the spray drying technique, CL-20 and nano-sized TATB@polydopamine (PDA) were effectively assembled into spherical co-particles with varying TATB contents (1, 5, and 10 %). The scanning electron microscopy images revealed the co-particles to have a football-shaped morphology. Notably, a part of the CL-20 had crystallised as a compact shell with a trace amount of nTATB@PDA on the surface, while most of CL-20 was embedded in the co-particles. The strong intermolecular interactions between the compact CL-20 shells and nTATB@PDA were confirmed through Raman and infrared spectroscopy analyses. For instance, the co-particles with 10 % nTATB@PDA exhibited 2 °C higher peak decomposition temperature compared to raw ε-CL-20, indicating improved thermal stability. Furthermore, thermal gravimetric analysis results revealed that the co-particles underwent one-step thermal decomposition, while the mixture decomposed in two steps (at the same ratio) due to the differing thermal stabilities of CL-20 and TATB. In terms of safety, the co-particles demonstrated an impact initiation energy of 16 J, which is five times higher than raw CL-20. Additionally, the friction sensitivity of co-TATBP10%/CL-20 decreased from 100 to 80 %. Despite great improvements in sensitivity, the density of the co-particles remained almost the same as that of ε-CL-20. Overall, these findings underscore the effectiveness of co-particle technology in reducing the mechanical sensitivity while enhancing the thermostability of CL-20, all whilst maintaining the energy density.