A Simple Route towards High-Concentration Surfactant-Free Graphene   Dispersions
  A simple solvent exchange method is introduced to prepare high-concentration and surfactant-free graphene liquid dispersion. Natural graphite flakes are first exfoliated into graphene in dimethylformamide (DMF). DMF is then exchanged by terpineol through distillation, relying on their large difference in boiling points. Graphene can then be concentrated thanks to the volume difference between DMF and terpineol. The concentrated graphene dispersions are used to fabricate transparent conductive thin films, which possess comparable properties to those prepared by more complex methods. 
Jiantong Li, Fei Ye, Sam Vaziri, Mamoun Muhammed, Max C. Lemme and   Mikael \"Ostling
cond-mat.mtrl-sci