Unifying dispersion properties of graphene oxide suspensions via interlayer spacing control: Insights for universal 2D colloid behavior

Abstract

Two-dimensional (2D) colloidal suspensions are versatile materials that can be fashioned into fibers, films, and complex 3D architectures through processes that are accompanied by shear forces. The broad applicability and final properties are determined by the correlations of microstructure and rheological properties of the suspension; however, the current level of knowledge on the microstructural causes of rheological properties is not sufficient to fine-tune the desired properties and to guide the development of applications.In this study, we investigated the rheological properties of graphene oxide (GO) suspensions as a model system of 2D colloids with varying concentrations and lateral sizes and correlated it to the microstructure through small-angle X-ray scattering and rheometry. Our findings indicate that the interlayer spacing between GO sheets determines their rheological properties as a key parameter, which involves concentrations and lateral sizes. We discovered a master curve of the rheological properties against the interlayer spacing between GO sheets, implying the universality of rheological properties of GO suspensions governed by their microstructure. Overall, our study provides efficient guidelines for tuning the rheological properties and macroscopic alignment of 2D colloids at the suspension and application levels.