Self-Healing Anticorrosive Coating Enabled by 8-Hydroxyquinoline-5-Sulfonic Acid-Doped Polyaniline: Synthesis and Applications

Abstract

The uncontrolled leaching of corrosion inhibitors from coatings into the environment, even when corrosion does not occur, causes environmental pollution and diminishes anticorrosion performance. To address these challenges, we developed an anticorrosive nanoscale additive based on 8-hydroxyquinoline-5-sulfonic acid-doped polyaniline (HQPA). The synthesized HQPA possesses synergistic anticorrosive properties due to the presence of PA, which provides anodic protection and creates a protective layer, and 8-hydroxyquinoline-5-sulfonic acid, which not only enhances compatibility between HQPA and the polymer matrix but also, as an organic corrosion inhibitor, further improves corrosion protection through cathodic protection. Electrochemical analysis substantiated that the HQPA anticorrosive pigment could provide significant corrosion protection to submerged bare steel in an aqueous saline solution by forming a passive layer and mixed cathodic/anodic protection. Additionally, it was revealed that steel coated with an epoxy coating containing only 1 wt% HQPA exhibits a corrosion rate approximately 10 times lower than that of coatings containing non-conjugated inhibitors. Furthermore, this coating possesses significant self-healing attributes, with a healing rate of 97.5%. This strategic approach paves the way for the development and commercialization of materials offering robust corrosion protection and self-healing features. © 2025 John Wiley & Sons Ltd.