Organic–Inorganic Coatings Based on Epoxidised Castor Oil/APTES/TEOS

Two series of organic–inorganic hybrid films were prepared from epoxidised castor oil (ECO) and the inorganic precursor 3-aminopropyltriethoxysilane (APTES), and the combination of APTES with tetraethoxysilane (TEOS) with different organic to inorganic proportions. Films were pre-cured at room temperature under inert atmosphere and subsequently submitted to thermal curing. The macro- and microscopic properties of the films, including adhesion, hardness, microstructure and thermal properties, were determined as a function of the proportion of ECO to inorganic precursors. Morphologic studies showed that the hybrid films were microscopically homogeneous. The hardness and tensile strength of the films increased with increased concentrations of inorganic precursor. All of the films exhibited good adhesion to an aluminium surface and worked as an efficient barrier against corrosion.