Evaluation of corrosion resistance of polydopamine-coated poly(o-toluidine)/titanium dioxide composite coatings

Addressing the inherent challenge of filler agglomeration in conductive polymer coatings, a polydopamine (PDA)-modified poly(o-toluidine)/titanium dioxide (PTA) hybrid was developed via oxidative polymerization. Structural characterizations reveal that the PDA-derived core-shell architecture effectively bridges the organic-inorganic interface, optimizing filler dispersion and chemical activity within the epoxy matrix. This modification leads to a denser coating microstructure that successfully impedes the diffusion of corrosive species. Electrochemical tests in 3.5% NaCl solution indicate that the PTA-EP system achieves a protection efficiency of 98.74%, with the corrosion current density suppressed to 1.78 × 10⁻⁷ A·cm⁻². Continuous immersion for 28 days confirms the durability of the system, which maintains a stable impedance modulus (|Z|_{0.01 Hz} ≈ 1.8 × 10⁴ Ω·cm²). This performance stems from the synergy of POT passivation, TiO₂ labyrinth effects, and PDA interfacial reinforcement. These results demonstrate the potential of PTA for sustaining long-term metal protection in aggressive environments.