Synergistic Effect of WO3 on Physico-chemical, Physico-mechanical, Hydrophobic, and Anticorrosive Performance of Poly-(melamine-co-formaldehyde)-Cured Pithecellobium dulce-Alkyd Nanocomposite Coatings.

Abstract

The development of sustainable, multifunctional, and volatile organic compound (VOC)-free nanocomposite coatings for advanced surface protection has emerged as a critical focus in the modern coatings industry. In this study, a novel bio-based nanocomposite coating system was developed using Pithecellobium dulce oil-derived alkyd (PDA), cured with a poly (melamine-coformaldehyde)-isobutylated resin (PDA-PMF80), and reinforced with tungsten trioxide (WO3) nanofillers, designated as WO3 @PDA-PMF80. The nanocomposites were synthesized via an in situ polymerization approach and applied to carbon steel (CS) substrates using a brush-coating technique. The structural, thermal, morphological, and hydrophobic properties of these nanocomposites were studied using FTIR, NMR, TGA, SEM, TEM, and contact angle measurements. Their Physicochemical and physico-mechanical properties were evaluated according to ASTM standards. The anticorrosive performance of these nanocomposite coatings was investigated in a harsh saline environment (5 weight % NaCl aqueous solution) using Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS). The WO3 @PDA-PMF 80 nanocomposite coatings demonstrated superior performance compared to PDA and PDA-PMF 80, with high corrosion protection efficiency (ɳ i ) of 99.99%, a low corrosion rate of 4.81×10 -4 mpy, and thermal stability up to 150°C. The WO3@PDA-PMF80 nanocomposite coatings exhibited better hydrophobicity, adhesion, mechanical strength, and excellent EC resistance performance, making WO3@PDA-PMF80 a promising candidate for industrial coating applications as compared to bare PDA, PDA-PMF80, and other systems reported in the literature.