Synergistic effect of diethylene triamine penta(methylene phosphonic acid) and graphene oxide barrier on anti-scaling and anti-corrosion performance of superhydrophobic coatings

Abstract

In this study, a novel diethylene triamine penta(methylene phosphonic acid) (DTPMPA)- and graphene oxide (GO)-modified superhydrophobic anodized aluminum (DGSAA) coating was fabricated. The obtained coatings were characterized by scan electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman analysis. After immersion in the supersaturated CaCO₃ solution for 240 h, the scaling mass of the DGSAA coating is only 50% of that of the SAA coating. The excellent anti-scaling performance of the DGSAA coating comes from three barriers of the air layer, the DTPMPA:Ca²⁺ chelate, and the lamellar GO, as well as the further active anti-scaling of DTPMPA:Ca²⁺ at the coating-solution interface. DTPMPA and GO at the surface of the DGSAA coating exhibit an insertion structure. In the electrochemical impedance spectroscopy measurement, the impedance modulus of the DGSAA coating is three orders-of-magnitude higher than that of the anodized aluminum. The synergistic effect of DTPMPA stored in the porous structure of anodized aluminum and the barrier protection of superhydrophobicity and GO contributes to the excellent comprehensive performance of the DGSAA coating. This research provides a new perspective for designing anti-scaling and anti-corrosion superhydrophobic bi-functional coatings.