Epoxidized Soybean Oil Cross-Linked Fluoropolymer Coatings: Electrochemical and Computational Approaches

The development of sustainable, high-performance coatings for corrosion protection is critical to meet industrial demands while addressing environmental concerns. Fluoropolymers, notably poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), are rendered one of the preferred choices for superior performance coatings attributed to their exceptional mechanical robustness, thermal resistance, and resistance to chemical attack. However, their low surface energy produces poor adhesion to metal substrates, limiting their application in critical corrosion-resistant systems. Conventional strategies for improving their adhesion often rely on hazardous chemicals or energy-intensive processes, leading to more environmentally detrimental practices. Herein, we demonstrate biobased, epoxy-fluoropolymer hybrid coating systems integrating hydroxyl-functionalized PVDF-HFP (PHOH) with varying epoxidized soybean oil (ESO) content, achieving enhanced adhesion, corrosion resistance, and mechanical durability. Experimental and computational analyses reveal that optimized epoxy cross-linking, particularly PHOH coating with 0.25 wt % ESO, enhances interfacial bonding via hydroxyl interactions, yielding a ∼3-fold increase in adhesion strength (1.40 MPa) and reduction in water diffusion compared to pristine PHOH. Further, the coating exhibits high hydrophobicity (121° contact angle) and electrochemical stability, where impedance values close to 106 Ω·cm2 are retained over 7 days of saline immersion. Quantum mechanical (QM) modeling further elucidates molecular-level interactions interplaying between the cross-linking intensity and protective performance shown by the high binding energy of the hybrid system (−35.01 kJ mol–1). By taking advantage of ESO’s low carbon footprint and eliminating harmful chemical precursors, this work outlines a practical route for incorporating renewable, low-toxicity materials into corrosion-resistant coatings while reducing the environmental burden of surface protection. The integration of biobased components into a fluoropolymer platform offers a stepwise pathway toward greener chemistries that can be adapted for existing industrial applications, such as corrosion-resistant coatings for chemical storage tanks and nonstick linings in cookware.