Interpenetrating network structure design and corrosion resistance of high-performance waterborne polyurethane coating modified by epoxy resin and functionalized graphene oxide

To obtain graphene oxide (GO) derivatives-based waterborne polyurethane (WPU) composite coatings with high anti-corrosion performance, microstructure, dispersion and interfacial adhesion of the coatings are key factors to consider. In this study, the waterborne polyurethane modified by epoxy resin (WEPU) and graphene oxide (GO) derivatives was synthesized by copolymerization, and its synergistic effect on the anti-corrosion properties of waterborne polyurethane (WPU) coating was investigated. For this purpose, the isophorone diisocyanate (IPDI) was grafted to the surface of GO. Then, the functionalized GO (iGO) was uniformly dispersed in the WEPU emulsions by a prepolymer method, which was attributed to strong interaction between iGO and WEPU, as proved by FTIR spectra and SEM images. The deterioration process of WEPU and iGO-WEPU coatings during the long-term immersion in 3.5 wt% NaCl solution was investigated by electrochemical impedance spectroscopy (EIS). The results indicated that the introduction of well dispersed iGO nanosheets into WEPU system enhanced the corrosion protection performance to substrate. Significantly, for the 0.9 wt% iGO nanosheets reinforced WEPU composite films, the contact angle value of iGO-WEPU composite films (94.7 & DEG;) reaches the highest in comparison with that of pure WEPU film (88 & DEG;), thus remarkably improving the water barrier property of iGO-WEPU coating.