Abstract
A waterborne epoxy coating with superior corrosion resistance was developed by using a novel amino-functionalized graphene oxide (GO) that was modified by 2,5-diaminobenzenesulfonic acid. A battery of characterization methods, such as Fourier transform infrared spectroscopy (FT-IR), Raman spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), was used to prove that DGO was successfully prepared by grafting the amino of 2,5-diaminobenzenesulfonic on GO. The results indicated that the surface of DGO became rougher than GO, but a complete sheet structure was still maintained after modification; the optimal modified GO could be achieved when the mass ratio of 2,5-diaminobenzenesulfonic acid and GO was 5:1. The electrochemical impedance spectroscopy (EIS) tests indicated that the impedance at 0.01 Hz of a coating with 0.2 wt.% DGO still remained at a relatively high value after immersion for 48 h in 3.5 wt.% NaCl, which was about one order higher than a pure waterborne epoxy resin coating, and the corrosion current density decreased from 3.76 × 10(-11) A/cm(2) to 3.62 × 10(-12) A/cm(2). The dry adhesion and wet adhesion increased to 1.90 and 1.22 MPa, respectively, and the adhesion loss decreased from 53% to 36%. These interesting features could make waterborne epoxy coatings a promising anticorrosion coating for metal in long-term protection.