Synthesis & characterization of dual-functional composite of poly(o-anisidine)/vanadium pentoxide/metal oxide for anticorrosion & flame retardancy application

This study presents a novel conducting polymer composite of Poly(o-anisidine) (POA), vanadium pentoxide (V₂O₅), and metal oxides (MO: ZnO, MgO, CeO₂) for corrosion resistance and flame retardancy. The POA/V₂O₅/MO composite matrix was synthesised using in-situ polymerisation, while the mixed metal oxides were produced via sol-gel technique. Protective coatings were prepared by incorporating the resulting composite into an epoxy formulation and applying it to metal surfaces, with polyoxypropylene diamine as the curing agent. FTIR, SEM-EDX, and XRD analyses demonstrated successful composite production and uniform dispersion of V₂O₅ and metal oxides in the polymer matrix. Flame-retardancy testing revealed that the coating received a UL-94 V2 rating, with a total burning time of 167 s and a maximum LOI of 21% at a 5% additive concentration. Mechanical tests revealed enhanced pencil hardness (6 H), impact resistance (45 kg · cm), and outstanding adhesion (5B), while preserving flexibility without cracking. Contact angle analyses showed increased hydrophilicity (38.28°), which promoted the formation of a protective surface layer. Electrochemical impedance spectroscopy and potentiodynamic polarisation showed that the 5% POA/V₂O₅/MO coating provided better corrosion protection by increasing charge transfer resistance and decreasing corrosion current density. These results show that the proposed composite offers a promising multifunctional and sustainable alternative for enhanced protective coatings.