• Title/Summary/Keyword: Liquid crystal

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Mechanism of Formation of Three Dimensional Structures of Particles in a Liquid Crystal

  • West, John L.;Zhang, Ke;Liao, Guangxun;Reznikov, Yuri;Andrienko, Denis;Glushchenko, Anatoliy V.
    • Journal of Information Display
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    • v.3 no.3
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    • pp.17-23
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    • 2002
  • In this work we report methods of formation of three-dimensional structures of particles in a liquid crystal host. We found that, under the appropriate conditions, the particles are captured and dragged by the moving isotropic/nematic front during the phase transition process. This movement of the particles can be enhanced significantly or suppressed drastically with the influence of an electric field and/or with changing the conditions of the phase transition, such as the rate of cooling. As a result, a wide variety of particle structures can be obtained ranging from a fine-grained cellular structure to stripes of varying periods to a course-grained "root" structures. Changing the properties of the materials, such as the size and density of the particles and the surface anchoring of the liquid crystal at the particle surface, can also be used to control the morphology of the three-dimensional particle network and adjust the physical properties of the resulting dispersions. These particle structures may be used to affect the performance of LCD's much as polymers have been used in the past.

Stressed Liquid Crystals

  • West, John L.;Zhang, Guoqiang;Glushchenko, Anatoliy
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.263-265
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    • 2003
  • Stressed liquid crystals, SLCs, consist of a lowdensity polymer network dispersed in a nematic host. We induced stress by shearing the material. Alignment layers are not required because the liquid crystal director uniformly aligns along the direction of shear. The shearing stress also eliminates light scattering and results in sub-millisecond switching speeds, making them good candidates for video display applications.

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Advanced LC Development for LCD TV Application

  • Tarumi, Kazuaki;Klasen-Memmer, Melanie
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.757-761
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    • 2004
  • Flat Panel Display (FPD) application of Television (TV) application is booming. Liquid Crystal Display (LCD) is forecasted to play a dominant role for TV application in next years. We review in this presentation LC material development for LCD TV application.

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Molecular Orientation and Optical Properties of Liquid Crystal Mixture Films of Photo-Reactive Mesogens and Non-Reactive Nematic Liquid Crystals (광경화성 액정과 비반응성 네마틱 액정 혼합 필름의 분자 배향 및 광학 특성)

  • Lee, Mong-Ryong;Shin, Mi-Young;Kim, Sung-Hyun;Song, Ki-Gook
    • Polymer(Korea)
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    • v.35 no.5
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    • pp.493-498
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    • 2011
  • Reactive mesogens were used to prepare photo-cured liquid crystal films in which orientations of liquid crystal molecules were preserved by crosslinked networks of cured reactive mesogens. The molecular orientations of liquid crystal mixtures of photo-reative mesogens and non-reactive nematic liquid crystals were studied and compared before and after curing reactions. The effects of temperature and the amount of the non-reactive nematic liquid crystal in the mixture on birefringence of the liquid crystal films were investigated. It was found that optical compensation films with different birefringence could be prepared by controlling the amount of the nematic liquid crystals in the reactive mesogen mixtures.

Developing 500 MHz NB 19F-13C Double Resonance Solid-State NMR Probe for in-situ Analysis of Liquid Crystal Display Panels

  • Choi, Sung-Sub;Jung, Ji-Ho;Park, Yu-Geun;Park, Tae-Joon;Park, Gregory Hyung-Jin;Kim, Yong-Ae
    • Bulletin of the Korean Chemical Society
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    • v.33 no.5
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    • pp.1577-1580
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    • 2012
  • The orientational and dynamic behavior of liquid crystal molecules on the alignment layer surfaces of liquid crystal display (LCD) devices is crucial to their performance, but there are only a few methods of experimentally elucidating the interactions between the liquid crystals and the alignment layers. Inspired by the natural and technical similarities between membrane proteins in lipid bilayers and liquid crystals in LCDs, we employed solid-state NMR methodologies originally developed for the study of membrane proteins in lipid bilayers for the in-situ analysis of liquid crystal display panels. In this article, we present a home-built 500 MHz narrowbore (NB) The orientational and dynamic behavior of liquid crystal molecules on the alignment layer surfaces of liquid crystal display (LCD) devices is crucial to their performance, but there are only a few methods of experimentally elucidating the interactions between the liquid crystals and the alignment layers. Inspired by the natural and technical similarities between membrane proteins in lipid bilayers and liquid crystals in LCDs, we employed solid-state NMR methodologies originally developed for the study of membrane proteins in lipid bilayers for the in-situ analysis of liquid crystal display panels. In this article, we present a home-built 500 MHz narrowbore (NB) $^{19}F-^{13}C$ double resonance solid-state NMR probe with a flat-square coil and the first application of this probe for the in-situ analysis of LCD panel samples. double resonance solid-state NMR probe with a flat-square coil and the first application of this probe for the in-situ analysis of LCD panel samples.

Synthesis and Physical Properties of Novel Fluorinated Liquid Crystalline Compounds

  • Keum, Hye-Won;Roh, Su-Dong;Do, Yun-Sun;Lee, Jae-Ho;Kim, Yong-Bae
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.1142-1146
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    • 2004
  • The synthetic route and physical properties for three-ring derivatives, trans-2,3,2',3'-tetrafluoro-4-alkyl-4'-(4-alkyl-cyclohexyl)-biphenyl and 4-alkyl-cyclohexane carboxylic acid 2,3,2',3',4'-pentafluoro-biphenyl-4-yl ester are presented. They exhibit broad range nematic phases exceeding 30K and low viscosity of nematic liquid crystal mixtures containing these materials. Their viscosity is compared with that of homologues with a lateral isothiocyanate group and show large negative dielectric anisotropies. The threshold voltage $V_{th}$ was low enough to be operated at a driving voltage of 5V. Our novel LC compounds are suitable materials for the improvement of dielectric anisotropy of vertical align liquid crystal displays (VA-LDCs).

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Infrared Spectroscopic Study of Molecular Hydrogen Bonding in Chiral Smetic Liquid Crystal

  • Jang, Won-Gun
    • Journal of Information Display
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    • v.2 no.3
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    • pp.18-31
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    • 2001
  • We utilize Fourier transform infrared (IR) spectroscopy to probe intramolecular hydrogen bonding in $smectic-C^{\ast}$ liquid crystal phases. Infrared spectra of aligned smectic liquid crystal materials vs. temperature and of isotropic liquid crystal mixtures vs. concentration were measured in homologs, both with and without hydrogen bonding. Hydrogen bonding significantly changes the direction and magnitude of the vibrational dipole transition moments, causing marked changes in the IR dichroic absorbance profiles of hydrogen bonded molecular subfragments. A GAUSSIAN94 computation of the directions, magnitudes, and frequencies of the vibrational dipole moments of molecular subfragments shows good agreement with the experimental data. The results show that IR dichroism can be an effective probe of hydrogen bonding in liquid crystal phases.

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Alteration of Physical Properties of Nanoparticle Embedded liquid Crystal Causing the Enhancement of the Performance of LCDs

  • Kobayashi, Shunsuke;Kineri, Tohru;Takatoh, Kohki;Akimoto, Mitsuhiro;Hoshi, Hajime;Nishida, Naoto;Toshima, Naoki;Sano, Satoru
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1473-1476
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    • 2008
  • Doping the nanoparticles of Pd, p-$BaTiO_3$, $SiO_2$ and MgO into LCs alters their physical properties such as $K_{ii}$, $\Delta\varepsilon$, ${\Delta}n$, $\gamma_1$ and $T_{NI}$. Except for $K_{33}$, all these parameters decreases and thus bring the reduction of operating voltage and/or response times.

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An Experimental Study on Temperature and Velocity Fields of the Turbulent Flows Horizontal Cylindrical Tube by Using Thermo-sensitive Liquid Crystal (수평원통 관에서 감온액정을 이용한 난류유동의 온도 및 속도장에 관한 실험적 연구)

  • 장태현;도덕희
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.7
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    • pp.921-929
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    • 2003
  • An experimental investigation was performed to study the characteristics of turbulent water flow in a horizontal circular tube by using liquid crystal. To determine some characteristics of the turbulent flow, 2D PIV technique is employed for velocity measurement and liquid crystal is used for heat transfer experiments in water. Temperature visualization was made quantitatively by calibrating the color of the liquid crystal versus temperature using various approaches (TLC technique: Thermochromic Liquid Crystal), and a neural-network algorithm was applied to the color-to-temperature calibration. This study shoud the temperature and time-mean velocity distribution for Re = 2,436, 2,500 and 2,724 along longitudinal sections and the results appear to be physically reasonable.