One-step functionalization of graphene by cycloaddition of diarylcarbene and its application as reinforcement in epoxy composites

Due to its novel physical, chemical and mechanical properties, graphene has great potential to be applied in composite science. However, the inert chemical structures with low surface energy and low solubility in both organic and aqueous solution are the major bottleneck for real applications. Chemical functionalization of graphene is one of the effective solutions to address the above challenges. In the present study, novel highly reactive diarylcarbene derivative is designed and synthesized. Different to previous approaches, this diarylcarbene derivative contains reactive epoxy groups, which can serve as anchoring sites for further modification. Then, reactive epoxy groups are introduced to graphene via one-step diarylcarbene cycloaddition. The modification is observed spectroscopically, and the obtained graphene (DC-GR) can be well-dispersed in organic solvent, such as acetone and dichloromethane. In order to further verify the effectiveness of modification, we use DC-GR as reinforcement to enhance epoxy resin. Both thermal and mechanical properties of the composites are improved significantly at low DC-GR content loading. The enhancement is believed to be attributed to the strong interfacial interactions between DC-GR and the matrix via epoxy groups. This study provides alternate strategy to modify the graphene, which will greatly expand the application field of graphene in composite science.