Corrosion protection of functionalized polyhedral oligomeric silsesquioxane (POSS) hybrid based coatings

Functionalized polyhedral oligomeric silsesquioxane (POSS) based materials were applied as coatings for pre-treatment of aluminium substrates. Organosilanes with specific functional groups were selected as additives to the POSS matrix. Layered double hydroxides (LDHs) pigments containing corrosion inhibitors were used to add a self-healing functionality to the coatings and increase the long-term protection performance against corrosion. The sol-gel derived hybrid coatings were applied using a bar coater and cured at various temperatures. Both filiform corrosion test and electrochemical impedance spectroscopy (EIS) measurements were used to assess the corrosion resistance of the coatings. The results showed that the combination of POSS with organosilanes gave a significantly improved adhesion of the coatings to Al substrate and enhancement of the cross-linking degree of the resulting network. Promising corrosion protection was achieved in several formulations after filiform testing. The coatings that performed well in filiform testing also showed good barrier properties, as revealed by EIS. The corrosion protection of the coatings with and without multifunctional additives (LDH loaded with selected corrosion inhibitors) will be investigated in association with the potential stimuli trigged release of corrosion inhibitor from the coatings.