The aluminum/polyethylene terephthalate interface: A joint theoretical and experimental study

The aluminum/polyethylene terephthalate interface is investigated with a combined theoretical and experimental approach, in order to understand the interactions occurring at the molecular level when the metal is deposited onto the polymer surface. The theoretical approach consists in performing quantum-chemical calculations on short molecular model systems interacting with a few Al atoms. The geometric structure of the organometallic complex is optimized and its stability as well as the changes in charge density due to Al bonding are evaluated. The theoretical results are compared to experimental x-ray photoelectron spectroscopy data collected during the early stages of interface formation. In particular, the evolution of the polymer core level peaks is paralleled to the Al-induced modification of the charge density on the model molecules. Al is found to react preferentially with the ester group by forming covalent bonds with the oxygen and/or the carbon atom of that group.