Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Spontaneous high-concentration dispersions and liquid crystals of graphene


Graphene combines unique electronic properties and surprising quantum effects with outstanding thermal and mechanical properties1,2,3,4. Many potential applications, including electronics and nanocomposites, require that graphene be dispersed and processed in a fluid phase5. 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.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Solubility and solvent quality of graphite dispersions.
Figure 2: G′ band Raman spectra performed using an excitation laser wavelength of 514 nm.
Figure 3: Evidence for single-layer dissolution.
Figure 4: Graphene as a rigid platelet.
Figure 5: Evidence for the graphene liquid-crystalline phase.

Similar content being viewed by others


  1. Segal, M. Selling graphene by the ton. Nature Nanotech. 4, 612–614 (2009).

    Article  CAS  Google Scholar 

  2. Novoselov, K. S. et al. Electric field effect transistor in atomically thin carbon film. Science 306, 666–669 (2004).

    Article  CAS  Google Scholar 

  3. Lee, C., Wei, X. D., Kysar, J. W. & Hone, J. Measurement of the elastic properties and intrinsic strength of monolayer graphene. Science 321, 385–388 (2008).

    Article  CAS  Google Scholar 

  4. Balandin, A. A. et al. Superior thermal conductivity of single-layer graphene. Nano Lett. 8, 902–907 (2008).

    Article  CAS  Google Scholar 

  5. Stankovich, S. et al. Graphene-based composite materials. Nature 442, 282–286 (2006).

    Article  CAS  Google Scholar 

  6. Schwamb, T., Burg, B. R., Schirmer, N. C. & Poulikakos, D. An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures. Nanotechnology 20, 405704 (2009).

    Article  Google Scholar 

  7. Ruoff, R. Graphene: calling all chemists. Nature Nanotech. 3, 10–11 (2008).

    Article  CAS  Google Scholar 

  8. Novoselov, K. S. et al. Two-dimensional atomic crystals. Proc. Natl Acad. Sci. USA 102, 10451–10453 (2005).

    Article  CAS  Google Scholar 

  9. Hummers, W. S. & Offeman, R. E. Preparation of graphitic oxide. J. Am. Chem. Soc. 80, 1339 (1958).

    Article  CAS  Google Scholar 

  10. Stankovich, S. et al. Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide. Carbon 45, 1558–1565 (2007).

    Article  CAS  Google Scholar 

  11. Becerril, H. A. et al. Evaluation of solution-processed reduced graphene oxide films as transparent conductors. ACS Nano 2, 463–470 (2008).

    Article  CAS  Google Scholar 

  12. Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation of graphite. Nature Nanotech. 3, 563–568 (2008).

    Article  CAS  Google Scholar 

  13. Valles, C. et al. Solutions of negatively charged graphene sheets and ribbons. J. Am. Chem. Soc. 130, 15802–15804 (2008).

    Article  CAS  Google Scholar 

  14. Lotya, M. et al. Liquid phase production of graphene by exfoliation of graphite in surfactant/water solutions. J. Am. Chem. Soc. 131, 3611–3620 (2009).

    Article  CAS  Google Scholar 

  15. Davis, V. A. et al. True solutions of single-walled carbon nanotubes for assembly into macroscopic materials. Nature Nanotech. 4, 830–834 (2009).

    Article  CAS  Google Scholar 

  16. Cremlyn, R. J. Chlorosulfonic Acid: A Versatile Reagent (The Royal Society of Chemistry, 2002).

  17. Melin, J., Furdin, G., Fuzellier, H., Vasse, R. & Herold, A. Action sur le graphite des solutions de chlorures dans l'acide chlorosulfonique. Mater. Sci. Eng. 31, 61–65 (1977).

    Article  CAS  Google Scholar 

  18. Rai, P. K. et al. Isotropic-nematic phase transition of single-walled carbon nanotubes in strong acids. J. Am. Chem. Soc. 128, 591–595 (2006).

    Article  CAS  Google Scholar 

  19. Ramesh, S. et al. Dissolution of pristine single walled carbon nanotubes in superacids by direct protonation. J. Phys. Chem. B 108, 8794–8798 (2004).

    Article  CAS  Google Scholar 

  20. Sumanasekera, G. U. et al. Electrochemical oxidation of single wall carbon nanotube bundles in sulfuric acid. J. Phys. Chem. B 103, 4292–4297 (1999).

    Article  CAS  Google Scholar 

  21. Cancado, L. G. et al. Measuring the degree of stacking order in graphite by Raman spetroscopy. Carbon 46, 272–275 (2008).

    Article  CAS  Google Scholar 

  22. Meyer, J. C. et al. On the roughness of single- and bi-layer graphene membranes. Solid State Commun. 143, 101–109 (2007).

    Article  CAS  Google Scholar 

  23. Onsager, L. The effects of shape on the interaction of colloidal particles Ann. NY Acad. Sci. 51, 627–659 (1949).

    Article  CAS  Google Scholar 

  24. Bates, M. A. & Frenkel, D. Nematic-isotropic transition in polydisperse systems of infinitely thin hard platelets. J. Chem. Phys. 110, 6553–6559 (1999).

    Article  CAS  Google Scholar 

  25. van der Kooij, F. M., Kassapidou, K. & Lekkerkerker, H. N. W. Liquid crystal phase transitions in suspensions of polydisperse plate-like particles. Nature 406, 868–871 (2000).

    Article  CAS  Google Scholar 

  26. Wensink, H. H. & Vroege, G. J. Isotropic-nematic phase behavior of length-polydisperse hard rods. J. Chem. Phys. 119, 6868–6882 (2003).

    Article  CAS  Google Scholar 

  27. Green, M. J., Parra-Vasquez, A. N. G., Behabtu, N. & Pasquali, M. Modeling the phase behavior of polydisperse rigid rods with attractive interactions with applications to single-walled carbon nanotubes in superacids. J. Chem. Phys. 131, 084901 (2009).

    Article  Google Scholar 

  28. van der Beek, D. & Lekkerkerker, H. N. W. Liquid crystal phases of charged colloidal platelets. Langmuir 20, 8582–8586 (2004).

    Article  CAS  Google Scholar 

  29. Chandrasekhar, S. Liquid Crystals 2nd edn (Cambridge Univ. Press, 1992).

  30. Campos-Delgado, J. et al. Bulk production of a new form of sp(2) carbon: crystalline graphene nanoribbons. Nano Lett. 8, 2773–2778 (2008).

    Article  CAS  Google Scholar 

  31. Jiao, L. Y., Zhang, L., Wang, X. R., Diankov, G. & Dai, H. J. Narrow graphene nanoribbons from carbon nanotubes. Nature 458, 877–880 (2009).

    Article  CAS  Google Scholar 

  32. Kosynkin, D. V. et al. Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons. Nature 458, 872–875 (2009).

    Article  CAS  Google Scholar 

  33. Talmon, Y. Transmission electron microscopy of complex fluids: the state of the art. Ber. Bunsen Phys. Chem. 100, 364–372 (1996).

    Article  CAS  Google Scholar 

Download references


The authors acknowledge the helpful input of Y. Kauffmann, H. Schmidt, C. Young, M. Majumder, A. Mela, W. Adams and B. Chen. Funding was provided by Air Force Office of Scientific Research (AFOSR) grants FA9550-06-1-0207 and FA9550-09-1-0590, Department of Energy (DOE) (DE-FC-36-05GO15073), Air Force Research Laboratories (AFRL) agreements FA8650-07-2-5061 and 07-S568-0042-01-C1, the Robert A. Welch Foundation (C-1668), US Army Corps of Engineers Environmental Quality and Installation Program under grant W912HZ-08-C-0054, the USA–Israel Binational Science Foundation and the Evans–Attwell Welch Postdoctoral Fellowship. Mitsui & Co. generously donated the MWCNTs used for preparing the nanoribbons. Cryo-TEM was performed at the Electron Microscopy of Soft Matter Laboratory, supported by the Technion Russell Berrie Nanotechnology Institute (RBNI). The HRTEM work was carried out at the Electron Microscopy Center at the Department of Materials Engineering, the Technion.

Author information

Authors and Affiliations



J.L. and N.B. conceived, designed and performed the experiments including dispersion and film fabrication. J.L. and A.S. performed AFM. N.B. and D.T. performed and interpreted the Raman measurements. N.B. characterized the liquid crystallinity. N.B. and A.N.G.P.V. designed the HRTEM experiments. A.S. fabricated the electronic devices. N.B., J.L. and A.S. performed electrical measurements. N.B. and A.S. performed SEM. N.B. performed STEM and electron diffraction. N.B. and A.L.H. prepared HRTEM samples, performed HRTEM experiments and interpreted the images. D.K. provided nanoribbons and graphite oxides. Y.T., Y.C., J.S., M.J.G. and E.K. performed HRTEM and cryo-TEM experiments and interpreted the images. N.B., M.J.G., A.L.H., A.S., J.L., Y.T., J.M.T. and M.P. co-wrote the paper. M.P., Y.T., Y.C. and J.M.T. supervised the project.

Corresponding authors

Correspondence to James M. Tour or Matteo Pasquali.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Rights and permissions

Reprints and permissions

About this article

Cite this article

Behabtu, N., Lomeda, J., Green, M. et al. Spontaneous high-concentration dispersions and liquid crystals of graphene. Nature Nanotech 5, 406–411 (2010).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing