pH-sensitive polymeric particles with increased inhibitor-loading capacity as smart additives for corrosion protective coatings for AA2024

The present work contributes to the design of smart anticorrosive coatings for corrosion protection of AA2024. Smart coatings, based on waterborne formulations modified with additives with high loading capacity of corrosion inhibitors open new opportunities for increased corrosion protection. In this work, a water-based epoxy coating was modified with Eudragit pH-sensitive particles. The particles are able to store a high amount of corrosion inhibitor (8-hydroxyquinoline) and to act as pH-sensitive reservoirs, dissolving at acidic pH values, releasing the stored inhibitor. The quantification of the loading capacity was determined by HPLC-MS/MS, using a methodology developed for this purpose. Electrochemical impedance spectroscopy (EIS) was used to discriminate the electrical parameters assigned to the barrier properties of the coating and to the corrosion inhibition ability of coatings modified with Eudragit particles. The self-healing ability in artificial defects was studied by localized electrochemical impedance spectroscopy (LEIS). The results highlight the use of Eudragit particles as pH-sensitive reservoir, its ability to store higher contents of inhibitor when loaded with 8-hydroxyquinoline, and its self-healing potential.