Constructing Reactive Nanopores at the Basal Plane of Graphene Oxide Toward Strong, Yet Tough Polyimide Composites

Covalently modified graphene is commonly used to enhance the performance of polymer composites. Optimizing the utilization efficiency of graphene oxide (GO) functional groups is key to improving the performance of the polymer composite. In this work, holey GO (HGO) with uniform 2-3 nm pores is prepared through chemical etching of the basal plane of GO. Subsequently, employing the edges of the nanopores as reactive sites, HGO is further reoxidized to obtain basal-plane carboxyl-modified HGO (C-HGO). Finally, via in situ polymerization at both the edge and basal planes of C-HGO, a C-HGO/polyimide (PI) composite film is produced. Compared to the pure PI film, the breaking strength of the 1 wt % C-HGO/PI film increases by 35.0%, and the fracture energy increases by 33.2%. In contrast, the breaking strength of the 1 wt % pristine GO/PI film increases by only 10.5%, while the fracture energy decreases by 83.5%. This work presents a novel modification of graphene to obtain strong, yet tough graphene/polymer composites.