Co-modification of polydopamine and KH560 on g-C3N4 nanosheets for enhancing the corrosion protection property of waterborne epoxy coating

In this work, the hydrophilic organic films were successfully coated on g-C3N4 nanosheets through facile comodification of dopamine (DA) and silane coupling agent (KH560). The co-modification of polydopamine (PDA) and KH560 on lamellar g-C3N4 greatly enhanced dispersion of g-C3N4 in aqueous solution and dramatically improved the compatibility and interfacial interaction with waterborne epoxy. The effect of incorporating modified g-C3N4 nanosheets into waterborne epoxy on anticorrosion performance for P110 steel substrates were demonstrated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and salt spray test. The results revealed that the vertical bar Z vertical bar(0.01Hz), value and percentage coating resistance (R-c) gain (eta(c)%) of nanocomposite coating increased by 977% and 90.72% with the addition of modified g-C3N4 nanosheets in comparison with pure waterborne epoxy coating, exhibiting outstanding anticorrosion abilities. The reinforced anticorrosion performances of nanocomposite coating could be attributed to the notable shielding effect and well dispersibility of modified g-C3N4 nanosheets.