Functional-group-dependent interfacial stabilization of additives in melt-cast explosives: Adsorption mechanisms under processing conditions

Stable interfacial adsorption in melt-cast explosives relies not only on the presence of functional additives but also on the ability of their surface functionalities to facilitate the formation of stable adsorption layers under stage-specific processing-related conditions. This study established and investigated a ternary interfacial model comprising HMX, functional additives, and DNAN through molecular dynamics simulations to elucidate how surface functionalization and stage-specific processing conditions regulate interfacial adsorption. Hydroxyl-, carboxyl-, and sulfonic-functionalized additives were comparatively evaluated based on equilibrium configuration, interfacial binding energy, radial distribution characteristics, concentration distribution, cohesive energy density, and mobility-related descriptors. Among the selected additives, the sulfonic-functionalized additive demonstrated the most robust interfacial stabilization, characterized by a stronger interfacial driving force, enhanced local ordering, and a more continuous adsorption layer adjacent to the HMX surface. Using this system as a representative case, the effects of temperature, pressure, and shear were further analyzed by correlating them with the key stages of melt-cast explosive formation. The results suggest that interfacial stabilization proceeds through selective interfacial capture, adsorption-layer reorganization, and final structural retention, and that this process is strongly affected by temperature, pressure, and shear. This work offers a molecular-level foundation for screening functional additives and understanding interfacial regulation in melt-cast explosives.