Theoretical investigations on CL‑20/TNBA co-crystal explosive via density functional method and molecular dynamics method

Abstract

The study of CL-20 co-crystal has always been a focal point within the field of energetic material modification. In this study, we employed the density functional method and molecular dynamics method to investigate the properties of hexanitrohexaazaisowurtzitane (CL-20)/ 2,4,6-trinitro-3-bromoanisole (TNBA) with different molar ratios ranging from 9:1–1:9. This investigation encompassed surface electrostatic potential, atomic interaction line, binding energy, trigger bond length, radial distribution function, cohesive energy density, and mechanical properties. Additionally, EXPLO-5 software was utilized to predict the detonation properties and products of pure CL-20, TNBA, and CL-20/TNBA systems. The results revealed significant differences in the surface electrostatic potential between CL-20 and TNBA molecules, indicating stronger interactions between different molecules than between identical molecules and suggesting the potential for co-crystal formation. At the molar ratio of 5:5, the binding energy was found to be the highest, signifying the most likely formation of a co-crystal. The main driving forces for co-crystal formation were electrostatic force and van der Waals force. The co-crystal explosive exhibited moderate sensitivity and excellent mechanical properties. Furthermore, the co-crystal detonation performance at a molar ratio of 5:5 was between that of CL-20 and TNBA, representing a new type of insensitive high-energy material.