Additive-free Gelation of Graphene Oxide Dispersion Induced by Mild Thermal Annealing

Graphene oxide (GO) exhibits good dispersibility and colloidal stability in an aqueous solution based on its functional groups on the basal plane and edges. These properties enable solution processing of GO for various forms of GO-based products such as fiber, membrane, aerogel, etc. In the processing of these applications, GO dispersions often require a proper phase transition to gel to have sufficient modulus. Conventionally, the gelation of GO dispersion occurs through the addition of polymer or salt; however, these additives act as impurities that can decrease the GO dispersibility and lower the electrical properties of the final product.

Here, we propose a strategy for additive-free gelation of GO dispersions through mild thermal annealing. The mild thermal annealing can floccuate GO particles and ultimately form a stable gel structures without significant reduction. We investigate the gel structure and rheological properties induced by the mild thermal annealing and discuss its ultimate electricl properties.