(298e) Comparison Analysis of 2D Nanomaterial Dispersions Partitioned By Differential Sedimentation Using Analytical Ultracentrifugation and Microscopy Methods

Differential sedimentation (DS) is a popular processing method for dispersions of 2D materials, enabling production of subpopulations with narrowed lateral size and layer thickness distributions. However, characterization and optimization of this centrifugation cascade methodology has relied on surface analysis characterization techniques with limited precision. Here, we use analytical ultracentrifugation (AUC), scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize subpopulations of graphene sheets generated through DS. AUC characterization of the colloidal 2D nanomaterial fractions in their native liquid-phase are compared to AFM and SEM characterization of deposited aliquots. Through these results we demonstrate the effectiveness of applying an additional cycle(s) of centrifugation at the same or at reduced acceleration to the pellet at each DS cascade step. This modified DS strategy is shown to result in a significant reduction of the dispersity of each DS cascade produced subpopulation relative to the common one-cycle methodology and this population change is readily discerned through AUC sedimentation velocity experiments.