Amphiphilic polymer modification of graphene oxide (AGO) to enhance the barrier and corrosion protection properties of waterborne polyurethane coatings

Surface coatings play crucial role in the field of anti-corrosive coatings. Graphene and its derivatives offer a combination of good barrier and labyrinth effect to enhance the corrosion performance of coatings. However, achieving good water dispersibility remains a considerable challenge for their use in waterborne coatings. Herein, we propose a facile strategy to enhance the water dispersibility of graphene oxide (GO), thereby expanding its application potential in waterborne coatings with improved corrosion resistance. The amphiphilic-modified graphene oxide (AGO) was synthesized by reacting amine-terminated polyalkylene oxide with the oxirane groups of GO for increased dispersibility in cardanol polyol-based waterborne polyurethane dispersion (WPU). The dispersion and film properties were evaluated as a function of the AGO content in the WPU, varying from 0 to 10 wt%. The WPU, AGO, and the nanocomposites were characterized for structure, morphology, particle size, optical and thermomechanical properties. The increased interfacial interaction between AGO and the WPU matrix was evident from the structural, optical and mechanical property evaluations. The AGO improved the barrier properties of the WPU composites, as revealed from thermal analysis and corrosion resistance properties. Electrochemical Impedance Spectroscopy (EIS) and Tafel extrapolation (Potentiodynamic Polarization) studies of WPU coating with 5 wt% AGO with an average film thickness of 15 +/- 5 mu m, provided 85% corrosion protection to mild steel substrates.