Fabrication of robust superhydrophobic epoxy/PANI@CNTs coatings with excellent anti-corrosion property

The application of superhydrophobic coatings in the corrosion protection field is limited by their poor surface structural stability, interfacial compatibility and adhesion strength. Herein, we prepared an epoxy/PANI@CNTs composite superhydrophobic coating with excellent mechanochemical stability by the combination of organic-inorganic hybridization and chemical modification. PANI@CNTs nanofillers synthesized by in-situ polymerization of aniline on the CNTs surface were used to construct the necessary nano-microstructures for superhydrophobicity and enhance the corrosion inhibition. The optimal coating showed high water contact angle of 159.5 ± 0.8° and low sliding angle of 3 ± 0.4°. The adhesion strength of the prepared coating attained the highest grade (GB/T9286) due to the formation of hydrogen bonds among polyaniline, silicon hydroxyl groups and the substrate surface. Moreover, the prepared coating maintained its superhydrophobicity even after 480 s of water impact, 1000 g falling sand impact or 500 abrasion cycles, which can be ascribed to the multi-interface enhancement generated by the organic-inorganic hybridization and the hydrogen bonds interaction. Furthermore, the prepared coating also possessed outstanding corrosion resistance with low-frequency impedance modulus remained at 4.79 × 10 8  Ω·cm 2 after immersion for 15 days, which was approximately three times that of the superhydrophobic coating without PANI@CNTs. This is mainly due to the triple protection mechanism formed by the air-film shielding, physical shielding of the coating and the synergistic passivation of polyaniline, endowing it with excellent anti-corrosion performance. Therefore, this study is expected to provide a theoretical reference for the application of superhydrophobic coatings in the corrosion protection of metal mechanical equipment.