Controlling the Optimum Surfactants Concentrations for Dispersing Modified Graphene Nanoplatelets (GNPs) in Aqueous Solution

To fully utilize the exceptional reinforcement potential of GNPs as a novel nanoscale material, achieving even dispersion within composites is essential. In this paper, the modified graphene nanoplatelets (GNPs) is prepared by the acidification method using a mixture of concentrated sulfuric and nitric acids. Then, four dispersants, including fatty alcohol polyoxyethylene ether (AEO), hydroxypropyl methylcellulose (HPMC), linear alkylbenzene sulfonate (LABS), and sodium alkyl alcohol polyoxyethylene ether sulfate (APES), are employed individually and combinatorially to disperse the modified GNPs in aqueous solution by the combination of ultrasonic processing. The modified GNPs treated by the method of acidification is analyzed using fourier-transform infrared spectroscopy (FTIR), and the corresponding ultrasonication-driven dispersion of modified GNPs in aqueous solution incorporated with various dispersants are characterized by UV–Vis spectroscopy and transmission electron microscopy (TEM). The experimental results indicate that the surface of modified GNPs has been grafted with abundant hydrophilic groups, including hydroxyl and carboxyl groups. All results show that the dispersant of AEO or HPMC in a certain concentration of 0.6 or 0.5 g/L has the maximum dispersion effect on modified GNPs in aqueous solution. With AEO and HPMC combined at a 5 : 7 concentration ratio and a total concentration of 0.4 g L^–1, the modified GNPs suspension achieves peak absorbance, demonstrating an excellent dispersion effect.