Data_NA-ART-04-2024-000328

Decisive role of electrostatic interaction on rheological evolution of graphene oxide under ultrasonic fragmentationDongpyo Hong,^a Matlabjon Sattorov,^b Ok Sung Jeon,^a Se Hun Lee,^a Gun-Sik Park,*^b Young Joon Yoo*^a and Sang Yoon Park*^cThe aqueous dispersibility and processability of graphene oxide (GO) are pivotal for various applications, including the fluid assembly of macroscopic materials and nanofluidic systems. Despite the widespread utilization of ultrasonic treatment to achieve homogeneous dispersions, the rheological changes of GO during sonication have remained relatively unexplored, leading to conflicting research findings. In this study, we demonstrate that the viscoelastic evolution of GO can significantly differ under ultrasonic fragmentation depending on the balance between repulsion force and attraction force at the initial state before fragementation. When electrostatic repulsion is in delicate equilibrium with attractive forces, gelation occurs under ultrasonic fragmentation, leading to increased viscosity under sonication. Conversely, when electrostatic repulsion predominates, viscosity decreases during sonication. This study reconciles conflicting observations on the rheological evolution of GO dispersion under ultrasonic fragmentation and provides valuable guidance and insights for the rheological engineering of GO colloidal systems.