Preparation of a Highly Stable Dispersion of Graphene in Water with the Aid of Graphene Oxide

Utilization of graphene (GE) in water is physically limited by its lack of functional groups, high hydrophobicity, and large interlayer van der Waals forces. Easy agglomeration of GE makes the preparation of GE-filled composites in an aqueous environment very difficult. Conventional methods solve this problem by introducing a surfactant to the system. However, the addition of a large amount of surfactant may hinder the performance of the composite. In this study, highly stable GE aqueous suspensions (remaining stable for more than 30 days) with a high concentration (1.5 mg/mL) were conveniently prepared by using graphene oxide (GO) as a stabilizer. A GE- and GO-filled rubber composite prepared by this GO-GE water suspension in an aqueous environment was also prepared and analyzed. It was found that a dual-network with dual functions was formed in the composite matrix: the GE network enhanced the electrical conductivity of the composite, while the GO network enhanced its mechanical properties. Our method is green, simple, and highly efficient, providing an alternative to improve GE's dispersion in water and synthesize GE-filled composites in an aqueous environment.