DOI: https://doi.org/10.55373/mjchem.v28i4.75

Keywords: Eugenol-benzoxazine, polyurethane copolymer, corrosion inhibitor, mild steel, bio-based coating

Abstract

A novel eugenol-based benzoxazine monomer (EuBz-ada) was synthesized via the reaction of paraformaldehyde, 3-amino-5-methylisoxazole, and eugenol, and its structure was confirmed by proton NMR, FT-IR, and UV-visible spectroscopy. The resulting monomer and its polyurethane-based copolymers were tested as corrosion inhibitors for mild steel; electrochemical polarization and electrochemical impedance spectroscopy (EIS) studies showed that the coatings containing EuBz-ada and different concentrations of polyurethane (PU) significantly increased corrosion resistance. Inhibition efficiency increased with PU content, confirmed by computational investigations using density functional theory (DFT), which suggested strong adsorption and favourable electronic properties. Further investigations showed a decrease in water absorption and an increase in gel content for the copolymeric coatings, which was in line with superior barrier properties. These results indicate the potential of bio-based EuBz-ada/polyurethane systems as effective and environmentally friendly corrosion inhibitors for mild steel protection.