Hexagonal Boron Nitride/Polyaniline Nanocomposites for Anticorrosive Waterborne Epoxy Coatings

The hexagonal boron nitride (h-BN) nanosheets have been used as nanofillers to improve the barrier properties of the waterborne epoxy (WEP) coatings. However, the h-BN nanosheets tend to agglomerate, which limits their anticorrosion applications. In this paper, the h-BN/polyaniline (h-BN/PANI) nanocomposites were prepared by the in situ polymerization of aniline on the surfaces of the h-BN nanosheets, which were further used to improve the anticorrosion performance of the WEP coatings. The structures of the as-prepared h-BN/PANI nanocomposites were investigated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The anticorrosion performances of the coatings were evaluated by electrochemical impedance spectroscopy. After immersion in 3.5 wt % NaCl solution for 28 days, the macro-morphologies and elemental changes of the substrate surfaces were analyzed by a 3D digital microscope and an energy-dispersive spectroscope, respectively. The results showed that the WEP coatings with the h-BN/PANI nanocomposites, especially that with 2 wt % h-BN/PANI nanocomposites, exhibited remarkably reinforced anticorrosion performance compared to the pure WEP coating. For the WEP coating, the coating with 1 wt % PANI, and the coating with 1 wt % h-BN, the substrates have been completely corroded. However, there was no obvious corrosion region for the coating containing 2 wt % h-BN/PANI nanocomposites. The superior anticorrosion performance of the coatings with h-BN/PANI nanocomposites was mainly attributed to the synergistic effect of the well-dispersed h-BN/PANI nanocomposites as the physical barrier and PANI as the corrosion inhibitor in this system.