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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]

Highlights • Inner reinforcement and outer modification have been combined for the first time to enhance the EP/CNFs coating. • The barrier and mechanical performances of EP/MoS 2 -CNFs have been improved compared with previous EP/CNFs coating. • The MoS 2 -CNFs composite was prepared via electrospun, which is a simple and effective method. • The relationship between mechanical property and corrosion resistance of coating has been discussed for the first. Abstract To enhance the anticorrosive and mechanical performances of carbon nanofibers (CNFs) in epoxy (EP) coatings, molybdenum disulfide (MoS 2) and γ- (2, 3-epoxypropoxy) propytrimethoxysilane (KH560) have been combined for inner reinforcement and outer surface modification based on CNFs. The electrochemical impedance spectroscopy, tensile testing and microhardness testing demonstrated that MoS 2 -CNFs (0.8%) composite can prominently enhance the anticorrosive and mechanical performance of the EP coating. Furthermore, the impedance of EP/MoS 2 -CNFs (0.8%) was higher than that of the pure EP and other composite coatings, and the Young's modulus (EY) and tensile strength (σs) of EP/MoS 2 -CNFs (0.8%) were increased by 65.4% and 56.6%, respectively. [ABSTRACT FROM AUTHOR]