Dielectric spectroscopy of isotropic liquids and liquid crystal phases with dispersed graphene oxide.
Dielectric spectroscopy of isotropic liquids and liquid crystal phases with dispersed graphene oxide.
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DOI：
10.1038/srep31885
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发表时间：
2016-08-24
影响因子：
4.6
通讯作者：
Dierking I
中科院分区：
文献类型：
--
作者：
Al-Zangana S;Iliut M;Boran G;Turner M;Vijayaraghavan A;Dierking I
制备了不同尺寸的石墨烯（GO），并在各向同性和夜间（各向异性）流体介质中分散，以较广泛的温度（25-60 oC）和频率范围（100 Hz – 2 MHz）进行了较大的饮食范围，研究了GO-滴剂的饮食放松行为。 ID。观察到掺杂的各向同性培养基，例如异丙醇IPA，比掺杂的热态nematic Mediup 5CB低得多。通过分散相互作用到Go薄片。释放频率降低，因为在溶解的各向同性的GO薄片上增加了偏光显微镜。 OPED 5CB。
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 oC) 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.