Green self-healing coating for corrosion protection of zinc

During the study, fist of all the corrosion rate of coated zinc in a 3.5 wt. % NaCl electrolyte solution was studied. Epoxy resin coatings loaded with polypyrrole/dodecyl benzene sulfonate/quaternised alkyl pyridine and polypyrrole/dodecyl benzene sulfonate nanocapsules were compared to a non-loaded resin coating.

The nanocapsule-loaded coatings exhibited improved self-healing corrosion inhibitory properties. The self-healing properties were characterised by swelling ratio, electrochemical impedance spectroscopy, tafel polarisation, open circuit potential (OCP), FESEM, and optical microscopic imaging. The results over a 50-day time interval confirmed the stable self-healing behavior with the corrosion protection of 99.87 % in the scratched coating, containing polypyrrole/dodecyl benzene sulfonate/quaternised alkyl pyridine nanocapsule.

Potentially synergistic effect

The controlled release of quaternised alkyl pyridine was monitored by fluorescence emission spectroscopy and fluorescence microscopic imaging. A potentially synergistic effect in corrosion protection and self-healing is expected to have happened by polypyrrole inhibitory properties, the formation of Zn(DBS)₂ complex, and the physical adsorption of quaternised alkyl pyridine on the metal surface.

The study has been published in Progress in Organic Coatings, Volume 147, October 2020.