Polydopamine functionalized graphene oxide nanocomposites reinforced the corrosion protection and adhesion properties of waterborne polyurethane coatings

In this work, a polydopamine (PDA)-functionalized graphene oxide (GO) nanocomposite was prepared by a simple and eco-friendly approach. The results recorded via FTIR, UV-vis absorbance spectroscopy, Raman, XPS spectral, as well as atomic force microscope (AFM) demonstrated the effective modification and overlay of PDA on the surface of GO. GO-PDA can be stably dispersed in aqueous solution, and GO-PDA was incorporated into waterborne polyurethane (WPU) by solution blending. The examinations of particle size analysis and zeta potential showed that the incorporation of GO-PDA can effectively improve the uniformity and stability of polyurethane aqueous dispersion. The observation results of SEM verified that PDA promoted the uniform dispersion of GO nanosheets in polymer coatings. The electrochemical impedance spectroscopy and salt spray test of the steel substrates coated with composite coatings confirmed that the incorporation of 0.5 wt% GO-PDA significantly enhanced the anti-corrosion performance of WPU. Compared with previous reports, the incorporation amount of GO-PDA was drastically reduced, and the corrosion protection of coating was effectively improved. In addition, the pull-off and contact angle tests also demonstrated improved adhesion strength and hydrophobicity of the coating. Only water was used as solvent in the whole preparation process of coating and its excellent corrosion protection make it promising in engineering.