Graphene Oxide as 2D Colloids

Abstract

Graphene and its oxidized form of graphene oxide (GO) have been of particular interest in material science due to their exceptional physical properties. However, relatively little attention has been paid to the GO dispersions although the state of dispersions directly affect to the material property. For example, GO can be well-dispersed in water due to their hydrophilic functionalities and form liquid crystals (LC); however, they easily form gels or glass around 1 wt%, which often act as an obstacle in GO based composite production. Thus, to understand the structure and dispersing mechanism of GO dispersions is an essential step before reaching the application stage. In this talk, the detailed structural and rheological studies for GO dispersions are introduced with extensive scattering and rheology experiments. We first systematically investigate the phase behavior and structural evolution of GO LC suspensions under various experimental conditions and disclose how the glass transition of GO dispersions is affected particularly in the presence of strongly interacting polymers. An intriguing observation was that adding polymer can effectively retard glass transition of GO in water. Furthermore, by varying polymer type, functionality, and molecular weight, the GO structures and LC properties can be changed significantly, suggesting the possibility of controlling the process conditions in GO employed applications.