Water-based polyurethane composite anticorrosive barrier coating via enhanced dispersion of functionalized graphene oxide in the presence of acidified multi-walled carbon nanotubes

Organic films and coatings, specifically those incorporating graphene oxide, offer many advantages as corrosion barriers due to the excellent shielding and tailorable characteristics of graphene oxide. A simple method was used to prepare a composite coating with polyurethane (PU) as a polymer matrix; gallic acid modified graphene oxide (FGO) flakes and acidified multi-walled carbon nanotubes (FMWCNTs) acted as nanoscale reinforcement. The presence of FMWCNTs improved the dispersion of FGO in PU, and the composite coating exhibited nearly no defects. The one-dimensional FMWCNTs and two-dimensional graphene oxide sheets attract each other to form a relatively stable layered structure, such that the graphene oxide sheets form a large shielding layer. The anticorrosion properties of the pristine PU and composite coatings were investigated by electrochemical impedance spectroscopy tests for 96 h. The composite coating reinforced by two carbon nanomaterials simultaneously underwent no corrosion after immersion for 96 h, and the corrosion resistance was better than that of the other coatings. The enhanced anticorrosion properties of the FMWCNT-FGO/PU composite coating are attributed to the fully exploited reinforcement effect from the network of FGO and FMWCNTs that is enabled via enhanced dispersion.