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• The h-BN was co-modified by mechanical exfoliation and chemical modification. • The PEI-BNNS/EP exhibits a superior and long-term anticorrosion performance. • The PEI enhances the crosslink density of EP and reduces the defects of coating. The hexagonal boron nitride (h-BN) has extensive promise for metal corrosion protection due to its good impermeability to gas and liquid. However, the practical application of h-BN in polymer composites is limited by surface incompatibility. Herein, we prepared a homogeneous dispersion of h-BN in water-borne epoxy (EP) matrix by mechanical exfoliation and chemical modification, in which the h-BN powder was ultrasonic to obtain partially hydroxylated BN and the products were modified with water-soluble branched poly-ethyleneimine (PEI) via Lewis acid-base interaction. The electrochemical test (EIS and potentiodynamic polarization) and salt spray test in NaCl solution were used to analyze the corrosion resistance performance of composite coatings. The results show that PEI-BNNS/EP coating has superior and long-term anticorrosion performance for P110 mild steel. The impedance modulus (Z f = 0.01 Hz) of PEI-BNNS/EP still has 6.63 × 107 Ω cm2 after 70 days immersion in the 3.5 wt. % NaCl solution. The PEI has an important role for enhancing the anticorrosion property of PEI-BNNS/EP coating, which increases the dispersibility and compatibility of h-BN in EP and the crosslink density of epoxy resin. Our study gives a strategy for the preparation of easy dispersion h-BN nanosheets in large quantities, thus broadening its practical application in the polymer material field. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) has great promise for metal corrosion due to its good impermeability to gas and liquid. However, it is difficult for h-BN to disperse in water-borne epoxy (WBE) matrix owing to its nature hydrophobicity. In this work, h-BN was non-covalently modified by graphene oxide (GO) to enhance the compatibility of h-BN for WBE. And the GO/h-BN composite was characterized by transmittance electron microscopy (TEM), Raman spectroscopy, UV–vis absorbance spectroscopy and X-ray photoelectron spectroscopy (XPS). The corrosion protection and barrier performance of GO/h-BN/WBE were evaluated by electrochemical impedance spectroscopy (EIS) and salt spray test, which indicated that the composite coating with 0.3 wt. % GO/h-BN (1:1 w/w) additive exhibited excellent barrier and corrosion protection properties owing to the synergistic impermeable performance of h-BN and GO. [ABSTRACT FROM AUTHOR]