(571c) Functionalized Single-Sheet Graphene by Oxidation and Thermal Expansion of Graphite: Exfoliation Mechanism and Characterization

Individual layers of graphite, termed graphene, are composed of a honeycomb arrangement of carbon atoms and are the basis of the fullerene and carbon nanotube structures. Graphene sheets are expected to have tensile modulus and ultimate strength values similar to that of single wall carbon nanotubes (SWCNT). Recent studies of graphene produced by a scotch-tape method have been shown to possess interesting electrical properties.¹ Graphene sheets, much like SWCNTs, are expected to serve as fillers for the enhancement of mechanical and electrical properties in composite materials.² A recent study performed in our laboratories has demonstrated the formation of individual chemically modified graphene sheets by oxidation and thermal expansion of graphite.³ However, the expansion mechanism and the characterization of the degree of exfoliation are not adequately understood in order to produce large quantities of this material consistently. In order to resolve these issues, we have studied the exfoliation mechanism and characterization of the material in greater detail. We conclude that this technique produces 80% single graphene sheets.

[1] Heersche, H.B.; Jarillo-Herrero, P.; Oostinga, J.B.; Vandersypen, L.M.K.; Morpurgo, A.F. Nature 446, 56-59 (2007).

[2] Ramanathan, T.; Liu, H; Brinson, L.C. J. Polym. Sci. B: Polym. Phys. 43, 2269 (2005).

[3] Schniepp, H.C.; Li, J.L.; McAllister, M.J. et al. J. Phys. Chem. B 110, 8535-8539 (2006).