Molecular Interactions of Electroadsorbed Carboxylic Acid and Succinic Anhydride Monomers on Zinc Surfaces

The interfacial bonding properties of succinic acid, myristic acid, and succinic anhydride molecules with a set of differently pretreated zinc samples have been investigated using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The molecules were selected to model the typically used carboxylic-based adhesives, coatings, and self-assembling monolayers. The differently pretreated oxidized zinc surfaces were found to be capable of adsorbing the monomers, resulting in the formation of carboxylates. The interactions between the three types of monomers and the zinc samples resulted in the formation of a bridging bidentate coordination state on all samples, implying the contribution of the same functional groups in the adsorption mechanism. Moreover, relative FTIR peak intensities were utilized to evaluate the molecular structures upon adsorption. It was found that a sufficiently positive potential promoted an interaction between the adsorbates depending on the applied experimental parameters. The interactions resulted in a structural rearrangement of the molecules and formation of different end groups. The structural variations are expected to represent different interfacial characteristics of the polymer coatings.