Morphological changes in graphene materials caused by solvents

Abstract The aim of this work is to determine the changes in morphology caused in thermally reduced graphene oxide (rGO) after it has been mixed with organic molecules with different surface properties. The morphology of the dried rGO after being mixed with 16 organic solvents was evaluated using statistically SEM analysis. The results obtained indicate that this process led, in some cases, to an increase both in the number of stacked layers and in the corrugation of each rGO sheet. The largest modifications were obtained after contact with organic solvents undergoing intramolecular interactions mainly governed by the hydrogen-bonding interactions (measured as the Hansen δh parameter) and the dipole-dipole molecular interactions (expressed by the Hansen δp parameter). On the other hand, the morphology of the rGOs remained unaltered when solvents with values of δp + δh in the range 10–26 MPa 1/2 were used. These results represent a useful guide for the preparation of graphene-based composites in which the morphology of the graphene in the mixture is a crucial parameter which affects their characteristics.