FTIR spectral characterization of thin film coatings of oleic acid on glasses: Part II. Coatings on glass from different media such as water, alcohol, benzene and air

Oleic acid thin film was coated on soda-lime-silicate (SLS) glass from different coating media such as benzene, ethyl alcohol, water and air with different coating times and concentrations. When the coating medium is benzene, relatively more COO-metal ion complexes formed on the substrate surface, resulting in a coating layer with a more rigid and ordered structure. This was caused by a high solubility of oleic acid and a lower metal dissolution rate of the glass substrate in the medium. The coating time was a less important factor on the ordering of molecular chains than the coating medium was. The effect of concentration was more significant when oleic acid is coated from ethyl alcohol or water rather than from benzene. When oleic acid is coated from benzene, the most highly-ordered molecular structure of coating layer was obtained even at lower concentration. This investigation reveals that the dissolution behavior of the substrate, the solubility of the coating material and the dissociation behavior of metal-carboxylate (COO-M) complexes significantly influence the interaction mechanism between the coating material and the substrate. These factors can be controlled by the selection of an appropriate coating medium; thus, we can design organic thin films with optimized properties.