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/cm² to 3.62 × 10⁻¹² A/cm². 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.

Epoxy resins have widespread applications across various industries, such as anticorrosive coatings, owing to their exceptional attributes. However, there is a constant demand for enhancements to their mechanical characteristics to cater to the requirements of unique and specialized conditions. In this work, graphene oxide modified by 4,4′-Oxydianiline (MGO) was prepared using a covalent grafting reaction. The MGO in epoxy resin composites exhibited a rougher morphology and thin layers with a superior tensile strength (38 MPa), elastic modulus (358 MPa), flexural strength (85 MPa), flexural modulus (957 MPa), and hardness (62 HD). The results indicated that the mechanical properties of epoxy resin are significantly improved by MGO and the improved mechanical properties of epoxy resin composites are due to the strong interfacial bonding between MGO and epoxy.

Waterborne epoxy resin (WEP) coatings are widely used in various fields due to their environmentally friendly properties, yet their corrosion resistance and shielding properties demand further refinement. In this work, melamine-modified graphene oxide (MGO) was synthesized using surface covalent functionalization, and a novel waterborne epoxy/modified graphene oxide coating (WEP/MGO) was prepared. The optimal modification effect was obtained by exploring different proportions of melamine, which led to significant improvements in the corrosion resistance of WEP. Furthermore, the corrosion protection efficiency of WEP/MGO coatings was systematically evaluated by examining the impact of different additions of MGO. The impedance modulus at the lowest frequency was increased from 3.77 × 10⁸ Ω·cm² of WEP to 2.85 × 10⁹ Ω·cm² after immersion in 3.5% NaCl for 48 h, when the addition of MGO was 0.1 wt.%. And the corrosion expansion at both the scratch and corrosion spot frequencies of the WEP-coated samples displayed a remarkable attenuation following exposure to salt spray for 300 h. The corrosion resistance and barrier properties of WEP coatings have been considerably enhanced.