First-PrinciplesModeling of Interfacial AdhesionStrength of Epoxy Resins on Copper Surfaces

The adhesion of polymers to metal surfaces is critical for technological applications such as corrosion protection, UV stability and electronic encapsulation. Polymer–metal adhesion strength is influenced by interfacial interactions, crystallographic orientations, surface morphology, oxidation states and functionalization strategies. However, the interplay among these factors and their combined effects on adhesion strength remain incompletely understood. This study employs density functional theory to systematically investigate the adhesion of diglycidyl ether of bisphenol A (DGEBA), sulfur-functionalized DGEBA, and curing agents (dicyandiamide, 2-ethyl-4-methylimidazole) on metallic copper (Cu) and copper oxide (CuO) across face-centered cubic (100), (110) and (111) crystallographic facets. Optimized geometries, bond lengths, interface morphologies and adsorption energies were analyzed, complemented by Bader charge analysis to provide insight into electron redistribution at the epoxy-metal interface. Adhesive forces were approximated from the derivative of the Morse potential energy curve. The results reveal that oxidized surfaces, particularly CuO(110), exhibit stronger adhesion, emphasizing the importance of facet orientation and surface chemistry. Morse potential parameters <i>D</i>_e and <i>a</i> offer valuable insights into adhesion behavior. Notably, Cu(110) exhibits a higher a value compared to other surfaces, indicating a slower decay of attractive forces with distance and unique adhesive properties. These findings enhance the understanding of how surface chemistry and crystallography influence adhesion, providing a framework for fine-tuning adhesive characteristics through leveraging surface-specific interactions to design high-performance adhesion systems.