Dispersity control and anti-corrosive performance of graphene oxide modified by functionalized nanosilica in waterborne polyurethane.

Graphene oxide (GO) is expected to be used in the field of waterborne polyurethane (WPU) anti-corrosive coatings due to its excellent barrier property, but the poor dispersibility of GO limits its application. The hydrophilic modification of GO, although improving its dispersity, will greatly reduce its anti-corrosive property. Here, a new method is provided to avoid seeking an appropriate modifier blindly. Via the interaction between the epoxy group and amine group, the aminated GO (NGO) can be modified by (3-glycidyloxypropyl) trimethoxysilane (KH560) functionalized-silica (f-SiO) nanoparticles, while the f-SiO is affected by KH560 due to its relatively hydrophobic alkyl side chain. Consequently, the hydrophobicity of the f-SiO modified NGO (f-SGO) can be regulated just by adjusting the amount of KH560, thereby achieving the balance of excellent dispersibility and anti-corrosive performance of the f-SGO nanosheets in the WPU. The electrochemical impedance and potentiodynamic polarization results showed that the anti-corrosive performance of the WPU hybrid was greatly improved by adding the appropriate amount of f-SGO. This research provides a new idea for GO application in waterborne coatings.