Preparation of SiO2-decorated GO sheets and their influences on the properties of castor oil-based polyurethane coating film

Graphene oxide (GO) acted as an inorganic filler has attracted great attention in the construction of polymer-based composite coating film. Nevertheless, the high surface area, obvious van der Waals forces, and abundant hydrophilic groups of GO result in its poor dispersion behavior and compatibility in hydrophobic polymer , which greatly limits its widespread practical application. To solve the above issue, we have prepared SiO 2 -decorated GO (GO-SiO 2 ) nanoparticles using the sol-gel hydrolysis method. The FTIR, Raman spectra, XPS and SEM analysis displayed that GO-SiO 2 nanoparticles were successfully constructed and the SiO 2 nanoparticles are covalently grafted onto GO sheet surfaces. Moreover, the GO-SiO 2 nanoparticles are further employed as inorganic fillers into the non-solvent UV-curable castor oil-based polyurethane acrylate (COPUA) systems for the preparation of composite coating films. Herein, the GO-SiO 2 nanoparticles can be uniformly dispersed in hydrophobic COPUA-based coating precursor, and have favorable compatibility with COPUA resin. The incorporation of GO-SiO 2 nanoparticles into the coating film matrix would slightly decrease the gel content of coating films (all gel contents are above 91.5 %) while improving the hydrophobic property of coating films. Furthermore, the thermal stability and mechanical performance of coating films have reasonably enhanced trends by the incorporation of GO-SiO 2 nanoparticles. The prepared coating films display favorable acid, alkali, and solvent resistance , and the high content of GO-SiO 2 nanoparticles is beneficial to aggrandize the anticorrosion performance of coating films. This work provides a universal approach to modify GO sheets and construct multifunctional modified GO/polyurethane composite film for coating application.