Nitrogen-doped graphene sheets as efficient nanofillers at ultra-low content for reinforcing mechanical and wear-resistant properties of acrylic polyurethane coatings

Abstract The enhancement to the mechanical and wear-resistant properties of polymer coatings plays a vital role for their application in hostile serving environment and nanofiller is effective for this destination. Herein, we systematically investigate a new nanofiller, nitrogen-doped graphene sheets (NGS), which possess a multilayer sheet-like morphology and share a good compatibility with water. After the incorporation of NGS into a two-component waterborne polyurethane (WPU), the mechanical and wear-resistant properties of NGS/WPU composite coatings significantly improve and wear resistance behaves best at an ultra-low content, reaching up to 0.05 wt‰. Wherein, Young’s modulus is elevated by 52.67% and tensile strength is appreciably boosted by 58.87%. Simultaneously, apparent reduction of weight loss of 78.74% is observed in the abrasion testing, and the ductility of NGS/WPU composite films is reduced by 48.38%. These make it possible that an ultra-low content of nanofiller efficiently reinforces polymer-based composites to achieve a trade-off between mechanical properties. Moreover, the wear-resistance mechanism is investigated, and the interaction between NGS and WPU segments is explored to find the reason that the mechanical and wear-resistant properties of NGS/WPU composite coatings are improved at an ultra-low content.