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-C 3 N 4 nanosheets through facile co-modification of dopamine (DA) and silane coupling agent (KH560). The co -modification of polydopamine (PDA) and KH560 on lamellar g-C 3 N 4 greatly enhanced dispersion of g-C 3 N 4 in aqueous solution and dramatically improved the compatibility and interfacial interaction with waterborne epoxy. The effect of incorporating modified g-C 3 N 4 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 |Z| 0.01Hz value and percentage coating resistance (R c) gain (η c %) of nanocomposite coating increased by 977% and 90.72% with the addition of modified g-C 3 N 4 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-C 3 N 4 nanosheets. A novel well-dispersed g-C 3 N 4 @(PDA + KH560) is successfully fabricated through the co-modification of PDA and KH560, which significantly enhances the corrosion protection performance of waterborne epoxy in comparison with g-C 3 N 4. Unlabelled Image • Co-modification of PDA and KH560 was firstly used to modify g-C 3 N 4 nanosheet. • Dispersion of g-C 3 N 4 in waterborne epoxy was notably improved via the co-modification. • The corrosion resistance of g-C 3 N 4 @(PDA + KH560) coating enhanced sharply. [ABSTRACT FROM AUTHOR]