Interactions between a neutral polymeric bonding agent and nitramine explosives and their influencing factors

Neutral polymer bonding agents (NPBAs) have proven highly effective in enhancing the interfacial bonding between the bonding matrix and nitramine explosives such as cyclic trimethylene trinitramine (RDX) and cyclic tetramethylene trinitramine (HMX). However, there is a lack of clear understanding of the mechanisms behind their interactions, and it has been found that NPBAs produce different interfacial bonding effects on RDX and HMX. To gain deeper insights into the molecular-scale interfacial interactions of nitramine explosives/NPBAs, this study investigated the molecular electrostatic potentials, intermolecular interactions, surface structural features, and interfacial adsorption of a NPBA onto nitramine explosives using the density functional theory and molecular dynamics (MD) technique. The results indicate that the N atom on the cyano group of the NPBA molecule can form weak hydrogen bonds C–H⋅⋅⋅NC and C–H⋅⋅⋅O with the H atoms in the RDX and HMX molecules. The strength of such weak hydrogen bonding interactions is affected by the electrostatic potential range of nitramine molecules. Additionally, the surface structure of the nitramine plays a critical role in the NPBA adsorption strength. Compared to HMX, RDX exhibits a narrower surface electrostatic potential range and smoother crystal surface, resulting in weaker intermolecular interactions between the NPBA and the RDX surface.