Smart nanocontainer-based anticorrosive bio-coatings: Evaluation of quercetin for corrosion protection of aluminium alloys

The present investigation describes a new contribution to the development of active anticorrosive films. The "phytochemical" Quercetin (QCT), a known secondary metabolite of plants, loaded in silica nanocontainers as the natural organic inhibitor was utilized to obtain active anticorrosive coatings. With an artificial defect induced on the epoxy nanocomposite coating and subsequent corrosion reactions, active corrosion protection was triggered. The optimum performance was achieved from the 1.0 wt.% loaded coatings. The unscratched nanocomposite coatings were also examined and revealed enhanced corrosion protection in comparison with the unmodified epoxy coating. The anticorrosive action of the bio-coatings was controlled by the release and reactions of the inhibiting component from the coating at pH 10. The corrosion protection offered by QCT was due to the chemical transformation experienced by QCT with pH influence involving possible autoxidation and polymerization processes. Both immersion and electrochemical corrosion tests were employed in the study to systematically evaluate the corrosion protection. Furthermore, a primary investigation was conducted to assess the antibacterial property of the bio-coatings which offered significant antibacterial protection to the aluminium alloy surfaces by inhibiting the growth of the biofilm-forming bacteria Pseudomonas nitroreducens. These findings encourage the exploration of bio-based coatings for enhanced anticorrosion protection of aluminium alloys.