Reinforcement of phosphorylated graphene oxide on the anticorrosive properties of waterborne acrylate-epoxy resin coatings

Phosphorylated graphene oxide (PedGO) was synthesized through the in-situ phosphate esterification method with urea as catalyst and then embed into waterborne acrylate-epoxy resin emulsion (AE) coating to modify the coating. The TEM and AFM indicated that phosphate was uniformly decorated on GO sheets, forming a large phosphorylated graphene oxide sheets. The PedGO improved the water vapor permeability and the coating adhesion strength after 30 days of immersion in 3.5% NaCl of AE coatings, respectively. Electrochemical impedance spectroscopy measurements (EIS) revealed that the PedGO-modified AE (PedGO/AE) was an outstanding barrier against corrosive media compared with AE or GO-modified AE (GO/AE). Scratch tests also showed that the corrosion-promotion effect of PedGO in AE was inhibited. The enhanced corrosion protection performance was observed because on the one hand the PedGO can greatly prolonged the diffusion pathway of corrosive media in the coating matrix; on the other hand the organic phosphate on the PedGO formed the passivation membrane with metal ions by chelation in the corrosion region, which can prevented the contact of corrosive medium and metal.