Synthesis of Ultrathin Functional Boron Nitride Nanosheets and Their Application in Anticorrosion

Hexagonal boron nitride (hBN) shows huge promise for metallic corrosion protection due to its excellent impermeability. However, the exfoliation and dispersion of hBN have proven to be very challenging, owing to the strong “lip–lip” interactions and inherent hydrophobic features. Herein, ultrathin IL-BN nanosheets were synthesized and simultaneously noncovalent functionalized by ionic liquid (IL) through a liquid ball milling strategy to achieve the good compatibility with epoxy (EP), which was characterized by scanning electron microscope (SEM), transmittance electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectronic spectroscopy (XPS), and UV–vis absorbance spectroscopy. Electrochemical measurements confirmed that the addition of 0.5 wt % IL-BN into the EP matrix significantly enhanced the anticorrosion capability of coatings. After 4 weeks of immersion in 3.5 wt % NaCl solution, the IL-BN-EP coating remained with a high coating resistance Rc of 5.6 × 109 Ω cm2, 4 orders of magnitude higher than EP (4.9 × 105 Ω cm2). SEM and Raman measurements also corroborated that the steel protected by IL-BN-EP was hardly corroded. Moreover, the passivation effect of IL-BN-EP coating was confirmed by potential polarization curve (PPC) tests at the coating defects. The superior anticorrosion performance of IL-BN-EP coating was mainly attributed to the synergistic effect of physical barrier and self-healing property endowed by the well-dispersed IL-BN hybrids.