Multidimensional synergistic anti-corrosion performance of BTA@OH-BN/PANI ternary composite coatings

To address the challenge of insufficient long-term protective performance in waterborne epoxy coatings (WEP) due to curing defects, this study successfully synthesized a ternary nanocomposite filler, BTA@OH-BN/PANI (BTP), through a chemical oxidation polymerization process. Hydroxylated hexagonal boron nitride (OH-BN) was employed as a functional scaffold, onto which the corrosion inhibitor benzotriazole (BTA) was loaded via a solution impregnation method. Camphorsulfonic acid-doped polyaniline (CSA-PANI) was then coated onto the surface using in situ polymerization. FT-IR, XPS, and FE-SEM characterization confirmed strong interfacial coupling between the components and the successful formation of the core-shell structure. Electrochemical impedance spectroscopy (EIS) results revealed that the BTP filler significantly improves coating performance through a multidimensional synergistic effect, including physical shielding, active repair, and interfacial passivation. At the scratch defect site, due to the responsive release of BTA and the passivation induced by PANI, the charge transfer resistance (R_ct) increased from an initial value of 13,200 Ω·cm² to 25,600 Ω·cm² within 24 h, demonstrating significant active impedance recovery. After a 90-day immersion in a 3.5% NaCl solution, the BTP-WEP substrate retained its bright metallic lustre. This study provides a solid theoretical and experimental foundation for the development of high-performance, synergistic active, and environmentally friendly marine anti-corrosion coatings.