Homogeneous dispersion of cellulose/graphite oxide nanofibers in water-based urushiol coatings with improved mechanical properties and corrosion resistance

A polymeric coating based on a reactive urushiol-based polymeric emulsion was synthesized by grafting cellulose nanofibers (CNF) and graphene oxide (GO) onto the urushiol backbone, followed by phase inversion to obtain a cellulose nanofiber-graphene oxide/water-based urushiol emulsion (GO-CNF/WU). Following silane treatment (APTES), well-dispersed CNF-GO composites were obtained due to molecular interactions at the interface (including covalent, π - π and hydrogen bonding) between CNF and GO, resulting in a WU polymer which served as a mixing matrix to stabilize and improve the resulting GO-CNF through chemical-crosslinking. As expected, the mechanical properties (hardness and adhesion) and anticorrosion protection of the WU films were improved considerably after incorporating GO-CNF composites at fairly low concentrations. Compared to the WU film, the coated tinplate with the GO-CNF/WU coating displayed higher anticorrosion efficiency, with a PE of 99%. In addition, the pencil hardness of the GO-CNF/WU coatings increased significantly, from 2 to 6H, and adhesion was remarkably enhanced from grade 6 to 1 after the addition of 10% MGO to the films. Due to the synergistic protective effect of CNF and GO, the method may represent a facile and environmentally friendly approach to integrate multi-nanoscale blocks into WU polymer with excellent mechanical properties and corrosion resistance.