▎ 摘　　要

Graphene and modified Graphene often can be used as effective reinforcer or cross-linker in self-healing materials. However, the influence of fillers sheets size on the self-healing materials remained unclear. In this report, we investigate the effect of different graphene oxide (GO) sheets size in the properties of self-healing Polyurethane. The different sizes of graphene oxide (GO) were prepared from various sizes of graphite via the improved Hummers' method. Furthermore, the corresponding maleimide functionalized GO (mGO) sheets were synthesized from maleimide modification processing. The X-Ray photoelectron spectroscopy (XPS) analysis shows that the smaller size GO, the higher oxidation and functionalization. We systematically investigated the influence of size GO and mGO on the mechanical and self-healing performance of Polyurethane/Graphene Oxide (PG) and Polyurethane/maleimide modified Graphene Oxide (PM) with the dynamic thermal reversible Diels-Alder bonds. The results show that GO sheets in smaller size produce an advantage on the mechanical and self-healing behavior. Moreover, the PM nanocomposites exhibited superior mechanical and self-healing properties compared to PG nanocomposites at the same loading.