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

Abstract

A metal−polymer interface is pertinent to numer ous 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.

Bond formation at polycarbonate | X interfaces (X = Ti, Al, TiAl) probed by X-ray photoelectron spectroscopy and density functional theory molecular dynamics simulations

“…Utilizing theoretical approaches to evaluate the interfacial bond formation of thin films with polymers, many studies focused on placing individual atoms at possible reaction sites of the polymers using ab initio-based calculations. This approach was recently used, for instance, to investigate the metalization of poly-epoxy with Cu [20] and Al [21] . While these small systems have the advantage of providing reasonable computational speed, they are a strongly simplified representation of the final state after deposition, whereas modeling the actual processes happening during the deposition is neglected.…”

Chemical Reaction and Bonding Mechanism at the Polymer–Metal Interface

“…They concluded that Cu atoms interact preferentially with hydroxyls to form Cu–O–C bonds at the interface. Similarly, in the work of Anand et al, based on the XPS analysis and DFT method, a suitable molecular model was determined to reveal the interaction mechanism at the atomic scale, which explained the formation of the Al/poly-epoxy interface.…”

High-Energy Electron-Irradiated Fluorinated Ethylene Polypropylene Copolymer Coatings on Al Substrates for Enhanced Metal Adhesion and Protection

“…The irradiation for Al-2 led to the formation of C–O–Al bonds between Al, FEP, and the terminal CH 3 groups that did not exist for Al-1. Compared with other reactive metals such as Ca, Cr, Fe, and Ni, Al is known to form stable oxides and to create strong C–O–M bonds. ,− The C–O–Al bonds intervened between the Al and FEP layers to drastically improve the interfacial adhesion. The CH 3 groups in Al-2 probably did not contribute to the interfacial adhesion.…”

“…However, the origin of the peak at 285.6 eV still needs to be explained. Anand et al 8 performed DFT calculations and comparative XPS analysis to validate the chemical interactions at the Al−poly-epoxy interface. They predicted that the CH 3 component appears at 285−286 eV in the XPS spectrum.…”

“…For decades, metal–polymer composites have played an important role in a wide range of industrial fields, including microelectronics, medical equipment, automobiles, and aerospace. − Among commercial polymers, fluorocarbon polymers (FPs) have excellent nonadhesiveness and low friction, in addition to high heat and chemical resistances. − These properties make FPs an ideal coating material for metal sliding parts in various industrial products. However, their nonadhesiveness also makes it extremely difficult for them to adhere to or combine with metals, which has prevented their wider application.…”