Eco-Friendly Polyurethane-Based Coatings: Synthesis, Structural Characterization, And Anticorrosion Applications On Mild Steel

Abstract

This work reports the synthesis and characterization of novel polyurethane-based coatings derived from a terephthaloyl chloride–4-hydroxyacetophenone monomer (NC) and its subsequent polymerization with isophorone diisocyanate (IPDI) to obtain polyurethane resin (NC1). The resin was further modified with acrylic polyol and groundnut powder to produce advanced coatings (NC1, NC2, and NC3). FTIR and NMR analyses confirmed the successful formation of aromatic and urethane linkages, along with ester functionalities introduced by modification. Thermal studies (DSC, TGA) indicated glass transition temperatures of 100–115 °C and degradation onset above 300 °C, demonstrating good stability. UV–Vis analysis revealed high optical transparency (>80%), while contact angle measurements showed enhanced hydrophobicity upon modification. Electrochemical studies (EIS, CV) established excellent anticorrosion performance on mild steel, with impedance values above 10⁶ Ω·cm² and suppressed redox currents. Incorporation of acrylic polyol (NC2) improved mechanical and thermal behavior, whereas the groundnut bio-filler (NC3) imparted eco-friendly reinforcement with superior corrosion resistance. These results highlight the potential of the synthesized polyurethane coatings as sustainable alternatives for industrial anticorrosion applications.