Research on the Dispersion of Functionalized Graphene Nanoplatelets (GNPs) in Aqueous Solution

Due to its exceptional mechanical, optical, electrical and magnetic properties, graphene is widely used to enhance and improve the mechanical, electrical, and electromagnetic shielding properties of composite materials. In the paper, functionalized GNPs are initially prepared through sulfuric acid and nitric acid treatment for dispersion in an aqueous solution. A subsequent method using methylcellulose (MC) as a dispersant along with ultrasonic processing is then employed to further improve the dispersion of the functionalized GNPs. Various techniques, such as UV–Vis absorbance, zeta potential, surface tension and adsorption isotherm, are employed to characterize the dispersing performance of the functionalized GNPs suspension. Additionally, the dispersion mechanism of the functionalized GNPs is analyzed by means of the transmission electron microscopy (TEM). Experimental results indicate that the optimal MC concentration for dispersing functionalized GNPs in aqueous solution is 0.6 g/L. TEM images reveal that MC effectively disrupts agglomerated bundles, significantly reducing the thickness of the functionalized GNPs. The dispersing mechanism involves the diaphragm and hydrophobic effects, which prevent the GNPs from aggregating.