• Title/Summary/Keyword: Cholesteric liquid crystal

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Study on Planar Orientation and Selective Reflection of Cholesteric Liquid Crystals (콜레스테릭 액정의 Planar 배열과 선택 반사 특성에 관한 연구)

  • Jung, Gap-Ha;Seo, In-Seon;Lee, Mong-Ryong;Choi, Suk-Won;Song, Ki-Gook
    • Polymer(Korea)
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    • v.34 no.3
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    • pp.242-246
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    • 2010
  • FTIR spectroscopy has been employed in order to quantitatively investigate the relationship between planar arrangements and selective reflectance of cholesteric liquid crystals. It was found that the selective reflection was enhanced as the amount of planar arrangements in cholesteric liquid crystals increased. Although the planar arrangements of cholesteric liquid crystals can be induced only by the shear force effect, it was more effective to use the alignment layer to obtain the perfect planar arrangements.

Wide viewing angle of reflective cholesteric liquid crystal display

  • Kwon, Jang-Un;Kang, Dae-Seung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.608-610
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    • 2003
  • In the paper, we have investigated the reflective cholesteric display based on the polymer stabilization. The bistability in the polymer stabilized cholesteric texture(PSCT) films was observed and wider viewing angle was achieved due to imperfect planar texture.

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Fabrication and electro optical properties of stressed liquid crystal cell

  • Lee, Jung-Min;Park, Jin-Seol;Kang, Dae-Seung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.681-682
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    • 2009
  • We fabricated a stressed liquid crystal cell by mixing liquid crystal with a photo-polymer. By carefully choosing the mixing ratio between liquid crystal and the polymer, and by suitable mechanical shearing of the substrates, we demonstrated feasible electro optical properties for displays.

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Synthesis of Cholesteric Liquid Crystal and Its Application as a Polarizing Component on the Optical Film (콜레스테릭 액정의 합성과 광학필름용 편광성분으로서의 응용)

  • Kim, Yong-Suk;Lee, Kwang-Yeon;Ahn, Cheol-Heung;Kim, Geon-Joong
    • Applied Chemistry for Engineering
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    • v.19 no.6
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    • pp.661-667
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    • 2008
  • In this study, cholesteric liquid crystal (CLC) was synthesized and applied as a polarizing component on the optical film of back light units (BLU) for LCDs. After mixing CLC with nematic liquid crystal, this mixture was fulfilled in the module consisting of two films and then its amplifying efficiency and polarizing ability for a planarly emitted light were examined to apply as a BLU polarizer film for increasing the brightness of light. The properties of CLC compound were tested by UV/Visible spectroscopy and polarizing optical microscopy (POM). Flexible spacer was made by linear carboxylic acid group of cholesteric derivatives between cholesterol mesogen units for one-axis orientation in each layer. The CLC containing film could be used as a module to increase the ability of polarization and to enhance brightness of BLU and to widen wavelength range by stacking the films.

Thermal Inspection of GFRP using Liquid Crystal (액정을 이용한 GFRP의 열적시험법에 관한 연구)

  • Kim, Y.H.;Kwon, O.Y.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.10 no.2
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    • pp.50-55
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    • 1990
  • Flaws in GFRP(Glass Fiber Reinforced Plastics) were thermally detected using cholesteric liquid crystals. Presence of flaws changes the thermal conductivity of GFRP, and disturbs heat flow. When a uniform heat source is applied, the surface temperature of flawed region is different from that of sound region. The surface temperature distributions were measured by thermo-optic properties of liquid crystal. Since the colors of liquid crystal indicate temperature distribution of GFRP surface, the thermal disturbance by flaws could be detected. The locations of flaws in GFRP could be determined from the distribution of liquid crystal colors.

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Preparation and Swelling Behavior of Cross-Linked Films of Hydroxypropyl Chitosan Possessing Cholesteric Liquid-Crystalline Order (Cholesteric 액정질서를 지닌 Hydroxypropyl Chitosan 가교필름의 제조와 팽윤거동)

  • 마영대;김경희
    • Polymer(Korea)
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    • v.24 no.3
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    • pp.418-430
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    • 2000
  • A new hydroxylpropyl chitosan (HPCTO) capable of forming both thermotropic and lyotropic liquid crystalline phases was synthesized by reaction of alkali chitosan with propylene oxide and its solid films cross-linked with glyoxal were prepared by casting the liquid crystalline solution in methanol. The thermal and swelling properties of the cross-linked films were investigated. The films displayed fingerprint patterns characteristic of cholesteric liquid-crystalline phase, and their pitches increased with increasing temperature and cross-linker concentration. The cross-linked samples exhibited an anisotropic swelling in both water and methanol, suggesting that the two-dimensional cross-linking preferentially performs between HPCTO molecules. The degree of anisotropy highly depended on the solvent, but hardly on the cross-linker concentration investigated.

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New Techniques for Fabrication of Flexible Plastic LCD's

  • West, John.L.;Novotny, Grea R.;Fisch, Michael R.;Heinman, David
    • Journal of Information Display
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    • v.2 no.4
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    • pp.15-18
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    • 2001
  • We report simple techniques to manufacture low-powered, high-resolution, reflective cholesteric displays using flexible plastic substrates. We use wax transfer printing to replace photo-lithography and incorporate polymer walls to increase the mechanical strength and lifetime of the displays. These printing methods can easily be adapted to roll-to-roll production.

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A True Cholesteric Columnar Liquid Crystal

  • Cho, I-Whan;Lim, Young-Soo
    • Bulletin of the Korean Chemical Society
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    • v.9 no.2
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    • pp.98-101
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    • 1988
  • A pure columnar cholesterogen based on the octasubstituted phthalocyanine $(PcH_2)$, S-(+)-2, 3, 9, 10, 16, 17, 23, 24-octakis[5-(dodecyloxy)-2-oxa-pentyl]-phthalocy anine(1a), is described. To evaluate a cholesteric character of 1a, the corresponding achiral $PcH_2$ 1b and the copper complex of chiral $PcH_2$ 1a (CuPc), S-(+)-2,3,9,10,16,17,23,24-octakis[4-(dodecyloxy)- 2-oxapentyl]-phthalocyanine(2a) were also prepared. The chiral 1a exhibited a typical cholesteric texture change in which the transition of platelet (blue phase) to fan-shape texture was observed (K-M-I), whereas the corresponding achiral 1b showed only a focal conic texture (K- M-I). This is the first instance of a pure columnar cholesterogen observed with discotic liquid crystal systems.

Synthesis and Properties of Side Chain Liquid Crystalline Polymers with Siloxane Flexible Chain

  • Park, Jong-Ryul;Bang, Moon-Soo;Choi, Jae-Kon
    • Elastomers and Composites
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    • v.52 no.3
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    • pp.173-179
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    • 2017
  • Side-chain liquid crystalline polymers having polysiloxane skeletons were synthesized by a thiol-ene reaction, using two kinds of mesogenic groups: a cholesteryl group for induction into a cholesteric liquid crystal phase and a triazomesogenic group for imparting light-sensitivity. All the synthesized polymers were crystalline, except the one with a single cholesteryl group. Crystallinity, glass transition temperature, and melt transition temperature increased with increasing content of the azomesogenic group. The polymer (P-C10A0) with a single cholesteryl group has a cholesteric phase, the one (P-C0A10) with a single azomesogenic group has a smectic phase, and those with both types of mesogenic groups showed both smectic and cholesteric phases. The temperature ranges of the two liquid crystalline phases in the co-polymers were independent of the contents of the two types of mesogenic groups. The rate of photoisomerization of the light-sensitive azobenzene group in the polymer decreased with increasing azobenzene content due to steric hindrance between the azomesogenic groups.