Functionalization of graphene with hyperbranched polyglycerol for stable aqueous dispersion

The application of graphene for some particular fields including biomedical engineering was hindered by its poor aqueous dispersivity and hydrophobic property. In this study, the strategy of the functionalization of graphene with hyperbranched polyglycerol (HPG) by a facile procedure was proposed. By the epoxy ring-opening hyperbranched polymerization of glycidol, graphene surface was grafted with HPG layer with rich hydroxyl groups. The content of polyglycerol on HPG functionalized graphene (HPG-G) was determined to be 55%. The results of fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS) and UV-Vis demonstrated that HPG was successfully grafted onto graphene sheets (GSs), and the aromatic and crystalline structure of graphene was maintained after HPG functionalization. The obtained HPG-G composites possess high hydrophilicity and can be dispersed well in water. Furthermore, no discernable precipitation was found in HPG-G aqueous solution even after three months of storage.