Chemical Interactions at the Al/Poly-Epoxy Interface Rationalized by DFT Calculations and a Comparative XPS Analysis

A metal-polymer interface is pertinent to numerous technological applications, especially in spatial sectors. The focus of this work is to elaborate on the metallization process of the poly-epoxy surface with aluminum thin films, using atomistic details. To this end, X-ray photoelectron spectroscopy (XPS) under ultrahigh vacuum and density functional theory calculations are employed. The interfacial bonding between Al atoms and the poly-epoxide surface, represented by a dimer model, is studied by determining adsorption energies and by simulating XPS spectra. The latter simulations are mainly performed using the ΔKS method, taking into account the initial and the final state effects. Simulated atom-by-atom metal deposition on model epoxy systems is attempted to further elucidate energetics of metallization and preferential arrangement of metal atoms at the interface. A fair agreement obtained between XPS experiments and computations rationalizes the interaction mechanism at the atomic scale explaining the formation of the Al/poly-epoxy interface. Electronic structure properties highlight the charge transfer from the Al atom(s) to dehydrogenated model epoxy system.