The effect of number of chemical bonds on intrinsic adhesive strength of a silane coupling agent with metals: A first-principles study

This paper presents a comparative investigation on intrinsic adhesive strength of a silane coupling agent with metal surfaces through first-principles calculations based on density functional theory. Focusing on a typical silane coupling agent, 3-aminopropyl triethoxy silane (APS), pure copper, and aluminum were selected as the bonding metal. A simple interface model of the silane coupling monomer on the metal surface was constructed under a tensile loading condition. When the number of chemical bonds at the interface is one, Cu has a smaller breaking strain of the bond with oxygen in the APS molecule than Al and demonstrates lower adhesive strength. On the other hand, as the number of bonds increases, the interface becomes stronger and the failure mode changes from interfacial debonding to intramolecular cohesive fracture. As a result, the adhesive strength is improved, and the effect is remarkable especially on the Cu surface. Graphical abstract