Additive-free Gelation of Graphene Oxide Aqueous Dispersion Induced by the 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 (network structure) to have sufficient modulus. The gelation of GO dispersion usually 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 (MTA). The MTA can flocculate GO particles and ultimately form a stable gel structure without significant reduction. The microstructure and rheological properties of MTA induced gels are investigated with extensive SAXS and rheological property studies suggesting the mechanism of gelation. The ultimate electrical properties of MTA based GO structures are also discussed.