May 30, 2010

New Method for Producing Bulk Quantitites of Graphene

Researchers from Rice University and the Technion-Israel Institute of Technology unveiled a new method for producing bulk quantities of one-atom-thick sheets of carbon called graphene.

* dissolve graphite in chlorosulphonic acid, a common industrial solvent.
* dissolve as much as two grams of graphene per liter of acid to produce solutions at least 10 times more concentrated than existing methods.
* Using the concentrated solutions of dissolved graphene, the scientists made transparent films that were electrically conductive and produced liquid crystals
* In liquid crystals, the individual sheets align themselves into domains, and having some measure of alignment allows you to flow the material through narrow openings to create fibers
Nature Nanotechnology - Spontaneous high-concentration dispersions and liquid crystals of graphene

Graphene combines unique electronic properties and surprising quantum effects with outstanding thermal and mechanical properties. Many potential applications, including electronics and nanocomposites, require that graphene be dispersed and processed in a fluid phase. Here, we show that graphite spontaneously exfoliates into single-layer graphene in chlorosulphonic acid, and dissolves at isotropic concentrations as high as ~2 mg ml^−1, which is an order of magnitude higher than previously reported values. This occurs without the need for covalent functionalization, surfactant stabilization, or sonication, which can compromise the properties of graphene6 or reduce flake size. We also report spontaneous formation of liquid-crystalline phases at high concentrations (~20–30 mg ml^−1). Transparent, conducting films are produced from these dispersions at 1,000Ω ^−1 and ~80% transparency. High-concentration solutions, both isotropic and liquid crystalline, could be particularly useful for making flexible electronics as well as multifunctional fibres.

21 pages of supplemental material

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