The Effect of Size Polydispersity of Graphene Oxide on its Solution Dispersity and Rheological Properties

Graphene oxide (GO) has been considered a promising material that could be employed in advanced materials science and engineering due to its outstanding mechanical and electrical properties. Noting the application of GO is initiated from the GO in solution, a fundamental understanding of GO dispersions as colloids should proceed to control the properties of GO-based application. Among many parameters determining the state of colloidal dispersion, the size and its distribution should be firstly considered, which ultimately determines the final physical properties. For example, the bidispersed GO in size is known to improve the electrical property compared to the monodisperse GO. The result awakens the importance of the size distribution of GO size again, requiring more systematic studies on the GO dispersions with precise control of the polydispersity.

In this regard, we investigate the dispersion structure of GO and its rheological properties in the solutions with a systematic change of GO polydispersity. An extensive series of experiments including a rheometer, polarized optical microscopy, and a small angle X-ray scattering reveal that the polydispersity indeed affects the GO dispersion from nano-scale to micro-scale and its rheological properties.