Structure-performance relationship of CL-20-HMX-based composite energetic materials revealed by molecular simulation

• This study reveals the roles of binder and Al powder on composite energetic materials. • Medium-range Al–O coordination enhances interfacial cohesion in composites. • Molecular dynamics reveal structure-performance links in energetic composites. Predicting the composite characteristics of polymer-bonded explosives (PBXs) holds significant scientific importance for propellant development, as they directly influence both the safety and processability of propellants. However, the structure-performance relationship of energetic materials has not been fully revealed and understood. In this study, molecular dynamics (MD) simulations were employed to systematically investigate the synergistic mechanisms by which binder, aluminum (Al) powders and temperature influence the properties of cocrystals or mixture explosives composed of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazoisowoodzane (CL-20) and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclohexane (HMX). The results show that the introduction of binder significantly enhances the plastic deformability of the system, thereby improving processability. And the Al powder restores the elastic modulus to a certain extent by strengthening intermolecular van der Waals interactions. While the presence of the binder results in a slight increase in sensitivity, the incorporation of Al counteracts this effect, achieving a balanced between mechanical performance and sensitivity. Radial distribution function (RDF) analyses confirm the formation of stable hydrogen bonding between the binder and explosive components, alongside localized medium-range order Al-O coordination interaction, that can reinforce interfacial binding strength. This work provides a theoretical foundation for the rational design of functional fillers and performance regulation in advanced propellant systems.