SiO2 mesoporous thin films as nanocontainers for corrosion inhibitors in self-healing anticorrosion coatings

Among the different alternative surface treatments developed in view of the coming prohibition of chromates in aeronautic applications, sol-gel coatings show very promising properties. These layers provide a barrier against aggressive environments. Moreover, their performance can be improved by introducing inhibitive agents in the coating. However, the direct introduction of corrosion inhibitors in the sol-gel compromises their barrier properties. Nanocontainers are consequently used for the storage of inhibitive agents and dispersed in the sol-gel matrix to avoid direct interactions between components. In case of scratch or when stimulated by external action, nanocontainers release active compounds which form a protective layer healing the defect. In this work, a mesoporous sol-gel thin film synthesized through \u93Evaporation Induced Self Assembly\u94 process was used as nanocontainer for 2024 aluminium protection. The mesoporosity developed through the layer was employed to host organic corrosion inhibitors inside the film and consequently to offer an active corrosion protection. Morphology of the layer was characterized using transmission electron microscopy (TEM) and adsorption porosimetry. High specific surface area and well-organized pores are obtained, providing high-load ability for active species. Incorporation of corrosion inhibitors in the mesoporosity was checked using qualitative and quantitative analyses. Kinetics of active agents release was studied by UV/visible spectroscopy. Successful incorporation in the sol-gel matrix and possible release of corrosion inhibitors were observed. The self-healing properties were underlined by immersion test in aggressive sodium chloride solution