(593e) Synthesis of Ultra Large Few-Layer Graphene Sheets Mediated by Newly Designed Macromolecular Surfactant

Graphene is a monolayer of sp2-bonded carbon atoms tightly packed into a two-dimensional honeycomb lattice. It is the single sheet basic building block unit for many carbon allotrope forms of other dimensionaly, e.g. CNT, fullerene, and graphite. Such 2D layers of sp2-bonded carbon have a number of interesting properties including ultra high electron mobility, zero effective electron mass, and in some cases semiconducting properties. Although at least 4 effective methods have been disclosed to produce graphene in the past few years, mechanical exfoliation is still the only method providing easy access to truly single layer graphene suitable for research. The goals of our project are to: (1) develop novel low temperature methods for producing graphene, (2) develop novel methods for producing graphene nanostructures, (3) explore the impact of graphene processing on graphene properties. PmPV is a conjugated polymer with long alkyl side chains that has been reported to be very effective in assisting with the exfoliation and solubilization of graphene flakes from graphite. Held together by pei-pei stacking interactions between graphene and the conjugated main chain, the long side chains help to solubilize the graphene flakes in solvent. In this presentation, a fast, simple, and efficient way to make large size, single layer graphene flakes is discussed. A new macromolecular surfactant was designed and synthesized for use in graphene exfoliation and dispersion. The new surfactant is superior to PmPV in that it produces larger graphene flakes with fewer layers for equivalent sonication treatments. The average lateral size of our few layer graphene flakes is about 10 um. Raman spectroscopy, TEM, HRTEM, AFM, SEM, EDX, and XPS were used to characterize the layer number, graphene structure, and purity of synthesized graphene sheet. In addition, using the new surfactant graphene flakes can now for the first time also be extracted directly from HOPG without any additional mechanical or thermal treatment. This new ability offers the promise of larger flakes of higher quality.