Polydopamine coated Co2(OH)2BDC nanosheets for anticorrosive reinforcement of water-borne epoxy coating

In this study, Co2(OH)2BDC, a 2D metal-organic-framework (MOF) nanosheet (Co-MOF, BDC = 1,4-benzenedicarboxylate), was modified by using hydrophilic dopamine (DA) to construct a new anti-corrosion coating with excellent interface compatibility. Two-dimensional (2D) nanomaterials have attracted considerable attention because of their excellent barrier properties. However, enhancing the interfacial compatibility of epoxy coatings filled with 2D nanomaterials remains a challenge. DA contains several amine and catechol groups, which can effectively improve the interfacial compatibility between epoxy resin and 2D nanomaterials. Furthermore, Co-MOF/WEC (WEC = waterborne epoxy coating) and Co-MOF-PDA/WEC (PDA = polydopamine) were applied to steel substrates to systematically evaluate their anti-corrosion performance. The results indicated that the incorporation of well-dispersed Co-MOF-PDA nanosheets improved the anti-corrosion performance of the pure epoxy resin coating. The maximum impedance radius was exhibited by the 0.5 wt% Co-MOF-PDA/WEC coating, whose impedance after 60 days decreased to 3.945 × 107 Ω cm2, three orders of magnitude higher than that of epoxy resin. Experimental results showed the successful synthesis of Co-MOF-PDA nanoparticles, and adding an appropriate amount of nanomaterials effectively increased the initial resistance value and slowed the corrosion rate. This method will promote the practical application of MOF materials in the field of anti-corrosion coatings.