Polyethylenimine-assisted exfoliation of h-BN in aqueous media for anticorrosive reinforcement of waterborne epoxy coating

Herein, h-BN powders were sonicated in an aqueous solution of polyethylenimine (PEI) to simultaneously exfoliate and functionalize h-BN nanosheets with Lewis acid-base interaction. The structure and morphology of PEI modified h-BN nanosheets (PEI-BNNSs) were characterized by FTIR, TGA, AFM and TEM. The as-prepared PEI-BNNSs were served as anticorrosive nanofillers for waterborne epoxy (EP) coatings on Q235 carbon steel. The corrosion behaviors of EP and PEI-BNNSs/EP coating systems in 3.5 wt % NaCl aqueous solution were evaluated by electrochemical workstation. It is worth noting that the protection efficiency (PE) values of 1 wt % PEI-BNNSs/EP and 2 wt % PEI-BNNSs/EP coating systems are as high as 99.99 % compared to EP coating systems. Moreover, the impedance modulus (vertical bar Z vertical bar(f = 0 .01 Hz)) of the 1 wt % PEI-BNNSs/EP coating system was 3-4 orders of magnitude higher than the EP coating after 90 days of immersion. The electrochemical results revealed that PEI-BNNSs can significantly enhanced the corrosion resistance of waterborne epoxy coatings.