Vanillin-derived schiff base poly (benzoxazine-PU-nano TiO₂) anticorrosive coating for mild steel

Abstract Mild steel corrosion under saline conditions poses a significant industrial challenge, necessitating sustainable and high-performance protective coatings. This study reports the development of a bio-based anticorrosive nanocomposite coating derived from a vanillin-based Schiff base poly(benzoxazine–polyurethane–TiO₂) system, which integrates the rigidity of polybenzoxazine, the flexibility of polyurethane, and the reinforcement of TiO₂ nanoparticles. The vanillin-based benzoxazine monomer was synthesized via the Mannich condensation reaction and characterized using NMR and ESI-MS (m/z = 313 [M + 1]). TiO₂ nanoparticles were prepared hydrothermally and incorporated into the polymer matrix with varying polyurethane concentrations. The hybrid coatings were fabricated through thermal curing and systematically characterized using FT-IR, UV–VIS, XRD, SEM, electrochemical techniques (Tafel polarization and EIS), water absorption, gel content, and Density Functional Theory (DFT/MEP) analyses. Graphical Abstract