Highly hydrophobic polyaniline nanoparticles for anti-corrosion epoxy coatings

Perfluorooctanoic acid doped polyaniline (PFOA/PANI) nanoparticles were successfully prepared through ultrasonication-assisted oxidation polymerization. The prepared PFOA/PANI nanoparticles exhibited high hydrophobicity and good dispersibility in ethanol, which could uniformly distribute in epoxy resin (EP) coatings to enhance their anti-penetrant efficiency towards corrosive media. The corrosion protection properties of PANI-contained coatings on Q215 steel were evaluated and compared through electrochemical impedance spectroscopy measurements in brine. The experimental results demonstrated the PFOA/PANI/EP coatings possessed higher corrosion performance than the EP coatings and HCl-doped PANI-contained EP coatings. Besides, dedoped PFOA molecules from PFOA/PANI nanoparticles can be adsorbed on the surface of steel to form a hydrophobic corrosion inhibition layer, which further improves the corrosion resistance. The impedance of PFOA/PANI/EP coatings continuously increased after the coatings were immersed in brine for more than 2 days, and the impedance modulus at 0.01 Hz was higher than 6 × 108 Ω·cm2 after 9 days. The novel method for the preparation of hydrophobic PANI nanoparticles proposed in this work may provide new ideas and methods for developing more high-performance anti-corrosion materials and promoting their applications in corrosion protection.