High performance anti-corrosion coating-based nano-cerium oxide loaded polybenzoxazine-polyurethane (nCeO ₂ /PBZ-co-PU) nanocomposites

Abstract Bio based benzoxazine (BZ) monomer was synthesized from vanillin and p-toluidine and polymerized with diverse concentrations (60%, 80% & 100%) of isocyanate hardener (PU hardener) and a fixed amount (wt5%) of cerium oxide nanoparticles (nCeO 2 ) to produce nCeO 2 reinforced polybenzoxazine (PBZ) co-polyurethane (PU) (PBz:PU:CeO 2 ) nanocomposites. The anti-corrosive properties of the prepared nanocomposite coatings on mild steel (MS) were investigated. The synthesized BZ monomer and nano CeO 2 were structurally elucidated from various characterization techniques including Ultraviolet–visible spectroscopy (UV–vis), Fourier Transform Infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy ( 1 H NMR), Scanning Electron Microscopy (SEM) and x-ray Diffraction (XRD). The neat polybenzoxazine (PBZ) and PBZ:PU:CeO 2 nanocomposites were then characterized by via UV–vis and FT-IR. The impacts of corrosion resistance of PBZ:PU:CeO 2 coating on MS was investigated by electrochemical impedance spectroscopy (EIS), Tafel plot and microscopic images. The potential dynamic polarization (PDP) and impedance studies showed that the MS had superior corrosion resistance, with protection efficiencies of 97.74% and 97.82%, respectively than other samples. The water contact angle measurements revealed enhanced surface hydrophobicity, with the increased WCA value (118°) after coating of PBZ:PU:CeO 2 onto the mild steel indicating improved surface uniformity and barrier properties. Thus, the exponential improvement in the resistance behaviour of PBZ owing to the optimum PU attentiveness (100%) could be broadly utilized for many industrial applications such as adhesives, coatings and corrosion protection systems.