Critical factors on corrosion protective waterborne coatings containing functionalized graphene oxide: A review

Waterborne coatings are an environmentally friendly alternative to solventborne coatings due to their low volatile organic chemical emissions, low toxicity and non-flammability. However, the presence of hydrophilic groups in waterborne coatings weakens their water resistance and compromises their stability and durability in service. Graphene materials play a prominent role in corrosion protection coatings, among which graphene oxide (GO) is very unique due to its easily tailored surface functionality. The functionalization of GO breaks some limitations in the application of graphene materials and provides new functionalities. In this review, the effects of functionalized GO (fGO) on the corrosion protection properties of waterborne coatings were discussed in terms of the coating integrity, interfacial adhesion, network formation, water resistance and corrosion inhibition. Physically, fGO layers can reduce the permeability of corrosive molecules by forming a barrier network, which requires good dispersion and appropriate filler content. Chemically, the functional groups grafted on fGO surfaces can react with the coating matrix at the interface, consume hydrophilic groups of waterborne coatings or carry corrosion inhibitors. In addition, functional properties of waterborne coatings such as electrical conductivity, antibacterial properties, photodegradation resistance, thermal and mechanical properties can be realized by the addition of fGO.