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Showing 1–7 of 7 results
Advanced filters: Author: Jang-Kun Song Clear advanced filters

  • Determining graphene domain size and distribution is important for realizing functional electronic devices. Here, the authors use liquid crystals to study graphene surfaces, via the liquid crystal molecules aligning with the domains, and use nematic to smectic transitions to study defects.

    • Jong-Ho Son
    • Seung-Jae Baeck
    • Jong-Hyun Ahn
    Research
    Nature Communications
    Volume: 5, P: 1-7

  • Although dispersions of aligned graphene oxide flakes are particularly attractive for electro-optic devices, controlling the alignment of the flakes by using electric fields has proved difficult. It is now shown that the macroscopic alignment of graphene oxide liquid crystals can be controlled through the application of weak electric fields when interflake interactions are sufficiently small, giving rise to the largest Kerr coefficient in a molecular liquid crystal.

    • Tian-Zi Shen
    • Seung-Ho Hong
    • Jang-Kun Song
    Research
    Nature Materials
    Volume: 13, P: 394-399

  • Spontaneous nematodynamic standing waves in liquid crystal medium is demonstrated. The standing wave manipulates the molecular orientation to form tunable periodic defect arrays with concentric director profiles, which can serve as optical vortex array inducer or as tunable micro-liquid crystal lens array. In addition, the standing waves hold unique features such as diagonal nodal lines, self-adaption to broad resonance frequencies, and a step-like increase of wavelength with increasing frequency. It also exerts asymmetric mechanical pressure that can relocate small particles. The results lead to new approaches in director manipulation, colloidal assembly, and singular optics.

    • L K Migara
    • Jang-Kun Song
    ResearchOpen Access
    NPG Asia Materials
    Volume: 10, P: e459

  • We demonstrate full-color reflection with first- and second-order Bragg reflections in a GO dispersion, and we use two fundamental approaches to manipulate GO photonic crystals, namely, bottom-up and top-down manipulation by controlling the Debye length and using shear or surface fields, respectively. Direct observation of the GO alignments using confocal microscopy reveals excellent layer-to-layer packing assembly and poor in-layer assembly, elucidating the nematic nature of GO rather than its lamellar mesophase. In addition, modulations of the local GO density and alignment enable us to demonstrate full-range color paintings, including chromatic and achromatic colors.

    • Tian-Zi Shen
    • Seung-Ho Hong
    • Jang-Kun Song
    ResearchOpen Access
    NPG Asia Materials
    Volume: 8, P: e296

  • Nematic and isotropic liquid phases can coexist within a narrow temperature window. Here, Kim et al. show how to control this mixed phase via thermal and dielectrophoretic manipulations, based on which nematic microfilaments in an isotropic medium, or vice versa, are demonstrated.

    • Soo-Dong Kim
    • Bomi Lee
    • Jang-Kun Song
    ResearchOpen Access
    Nature Communications
    Volume: 6, P: 1-8