Study on the surface energies and dispersibility of graphene oxide and its derivatives

Recent research has highlighted a remarkable growing focus on surface properties and dispersibility of graphene. In this study, we fabricated four types of surface-modified graphene oxide and its derivatives with different C/O ratios by facile chemical methods. The extent of modification, surface energies, and dispersibility of the as-prepared samples were investigated through elemental analysis, X-ray photoelectron spectroscopy, contact angle, inverse gas chromatography, dynamic multiple light scattering method, and atomic force microscope. Results demonstrated that surface energies are affected by functional groups and C/O ratios significantly. The higher the proportion of polar oxygen-containing groups of materials is, the larger the values of polar surface energies and total surface energies are. Dispersibility of graphene oxide and its derivatives depends not only on surface groups and degree of modification of samples, but also on Hansen solubility parameters of solvents. As a result, we proposed a predicted template to screen the ranges of potential graphene solvents. Such a research presented here would facilitate preparation of graphene-polymer composites and development of graphene-based materials.