title: Dielectric spectroscopy of isotropic liquids and liquid crystal phases with dispersed graphene oxide.
abstract: Graphene oxide (GO) flakes of different sizes were prepared and dispersed in isotropic and nematic (anisotropic) fluid media. The dielectric relaxation behaviour of GO-dispersions was examined for a wide temperature (25-60 (o)C) and frequency range (100 Hz-2 MHz). The mixtures containing GO flakes exhibited varying dielectric relaxation processes, depending on the size of the flakes and the elastic properties of the dispersant fluid. Relaxation frequencies of the GO doped isotropic media, such as isopropanol IPA, were observed to be much lower than the GO doped thermotropic nematic medium 5CB. It is anticipated that the slow relaxation frequencies (~10 kHz) could be resulting from the relaxation modes of the GO flakes while the fast relaxation frequencies (~100 kHz) could indicate strongly slowed down molecular modes of the nematogenic molecules, which are anchored to the GO flakes via dispersion interactions. The relaxation frequencies decreased as the size of the GO flakes in the isotropic solvent was increased. Polarizing microscopy showed that GO flakes with a mean diameter of 10 μm, dispersed in water, formed a lyotropic nematic liquid crystal phase. This lyotropic nematic exhibited the slowest dielectric relaxation process, with relaxation frequencies in the order of 2 kHz, as compared to the GO-isotropic suspension and the GO-doped 5CB.
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
authors.forename: Shakhawan
authors.initials: S
authors.lastname: Al-Zangana
authors.affiliation: School of Materials and National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
authors.forename: Maria
authors.initials: M
authors.lastname: Iliut
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.|Physics Department, Bogazici University, Istanbul, 34342, Turkey.
authors.forename: Gökçen
authors.initials: G
authors.lastname: Boran
authors.affiliation: School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Turner
authors.affiliation: School of Materials and National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
authors.forename: Aravind
authors.initials: A
authors.lastname: Vijayaraghavan
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
authors.forename: Ingo
authors.initials: I
authors.lastname: Dierking