Computation of Binding Energy of MCS and GO-Grafted MCS with Waterborne Epoxy Resin Using Density Functional Theory Method: Investigating the Corrosion Resistance of the Composite Coatings

In order to overcome the problems of poor corrosion resistance and low hydrophobicity of water-based coatings. Two corrosion-inhibiting materials, graphene oxide (GO) and modified chitosan (MCS), were added to the coatings to obtain a new type of coating with comprehensive properties. The composite material formed by PVA cross-linked waterborne epoxy resin was named "substrate". The density functional theory (DFT) calculation was used to explore the binding ability of MCS and GO-grafted MCS to the substrate, respectively. The results showed that the complex cross-linked network structure formed by the grafting of GO and MCS not only improved the intermolecular interaction force but also improved the binding ability to the substrate, and the coating is denser, effectively delaying the erosion to the coating by the corrosive medium. The composite coating exhibited excellent dual functional properties of hydrophobicity and corrosion resistance at the coating-metal interface, and a stronger protective effect was formed upon the steel plate. Studies showed that this composite coating has good hydrophobic properties. (The contact angle of the composite waterborne coating reaches 87°.) It also has low self-corrosion current (0.28/cm^-2) and high corrosion voltage (-0.45 V). The maximum inhibition efficiency of the coating is 99.97%.