Superhydrophobic polyaniline/TiO2 composite coating with enhanced anticorrosion function

Abstract

The combination of superhydrophobicity and electrical conductivity to enable new functionalities of conductive polymers is of great potential in anticorrosion applications of metal and alloy. In this work, a rough Zn coating was fabricated on carbon steel substrate through an electrodeposition process. The Zn-coated carbon steel substrate was further coated by a modifier that contains polyaniline/TiO2 composite (PTC) and stearic acid (STA), to develop a superhydrophobic and corrosion resistant STA/PTC (SPTC)-Zn coating. The surface morphology study found that there were numerous stamen/pistil-like protrusions on the SPTC-Zn coatings. The results of wettability test show that the SPTC-Zn coating has a water contact angle (WCA) of 159.8° and a water sliding angle (WSA) of 6.2°, which exhibits gratifying superhydrophobicity. Moreover, the superhydrophobic SPTC-Zn coating also displays superior scratching/peeling resistance, abrasion resistance, acid-alkali resistance, corrosion resistance and self-cleaning properties, indicating that the modifier-containing PTC could significantly improve the mechanical and chemical stabilities, antifouling and anticorrosion properties of Zn coatings. It can be inferred that the excellent performance of SPTC-Zn coating was mainly derived from the synergistic effect of the following three aspects: the air cushion stored in its hierarchical micro/nanostructures transforms the traditional solid-liquid contact into solid-gas-liquid separation, the formation of series hydrophobic complexes on the coating surface, and the composite passivation film generated by the oxidation zinc substrate of conductive polyaniline. Based on this new protection mechanism, the obtained superhydrophobic SPTC-Zn coating displays promising potential in practical industries.