▎ 摘　　要

The enhancement of the mechanical and wear-resistant properties of polymer coatings plays a vital role for their application in hostile serving environments, and nanofiller is effective for this purpose. Herein, we systematically investigate a new nanofiller, nitrogen-doped graphene sheets (NGSs), which possess a multilayer sheet-like morphology and share a good compatibility with water. After the incorporation of NGS into a 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 0.005 wt% (50 ppm). Furthermore, Young's modulus is elevated by 52.67% and tensile strength is appreciably boosted by 58.87%. Simultaneously, an 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, with low cost in the wear-resistance related field.