Self-healing supramolecular polyurethane coatings: preliminary study of the corrosion protective properties

This paper consists of an investigation of the protective properties of a new polyurethane coating (supramolecular polymers) based on hydrogen bonding. It means that the covalent bonds are partially substituted with hydrogen bonds, which are able to induce self-healing properties in the coating after thermal treatment. The idea is to evaluate if the self-healing ability can restore the barrier properties, and therefore the protective properties, in the case of damaged (scratched) coatings for corrosion protection. The corrosion protection properties characterisation has been carried out using electrochemical impedance spectroscopy measurements. The barrier properties are strictly related to the covalent bonds networks in this class of materials, at least for percentages of hydrogen bonds replacement until to 25%. Some partial recovery after artificial defect has been demonstrated, even it is not sufficient at the moment, and with quite large defect, to completely recover the protective properties. The present preliminary work demonstrates that the potential of multiple hydrogen bonds can be effectively exploited in coating applications owing to the combination of improved damage response behaviour and protection from corrosion phenomena. Further experimental work will be carried out in order to verify if, for smaller dimensions, the complete recovery of the system can be obtained.