Enhanced performance of hybrid polyurethane thin coatings: synthesis and characterization via sol–gel method using TEOS and VTMS

Hybrid polyurethane thin coatings have gained significant attention in the surface coatings domain due to their superior mechanical, thermal, and chemical attributes. In this study, a hybrid coating was developed by integrating an organic component (acrylate-terminated PU) with an inorganic component (tetraethyl orthosilicate-vinyltrimethoxysilane) (TEOS-VTMS sol), resulting in an inorganic-organic hybrid system that was subsequently applied to a mild steel panel using a dip-coating technique. The organic component was synthesized by reacting polyester polyol, which was produced from 1,6-hexanediol and adipic acid, with IPDI (isophorone diisocyanate), and then terminating the resulting prepolymer with HEMA (2-hydroxyethyl methacrylate). The inorganic component was prepared by reacting TEOS and VTMS in the presence of ethanol and acetic acid. The hybrid coating was then formed by reacting the TEOS-VTMS sol with the acrylate-terminated PU using benzoyl peroxide as a catalyst. Characterization of the polyester-based polyol and the acrylate-terminated PU was conducted using FTIR, DSC, and TGA. The hybrid coating system’s properties, including contact angle, chemical resistance, corrosion resistance, and mechanical properties, were thoroughly evaluated. Among the three hybrids tested (VTMS-PUA 1, VTMS-PUA 2, and VTMS-PUA 3), VTMS-PUA 3 demonstrated the highest corrosion resistance, exceptional hardness, flexibility, and chemical resistance, outperforming the other two hybrids.