Measurement of Multicomponent Solubility Parameters for Graphene Facilitates Solvent Discovery

We have measured the dispersibility of graphene in 40 solvents, with 28 of them previously unreported. We have shown that good solvents for graphene are characterized by a Hildebrand solubility parameter of delta(T) similar to 23 MPa1/2 and Hansen solubility parameters of delta(D) similar to 18 MPa1/2, delta(P) similar to 9.3 MPa1/2, and delta(H) similar to 7.7 MPa1/2. The dispersibility is smaller for solvents with Hansen parameters further from these Values. We have used transmission electron microscopy (TEM) analysis to show that the graphene is well exfoliated in all cases. Even in relatively poor solvents, >63% of observed flakes have <5 layers.