• Title/Summary/Keyword: 콜레스테릭

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Reduction of Color Shift Using Dichroic Dyes in a Cholesteric Liquid Crystal Cell (콜레스테릭 액정 셀에서 염료를 이용한 Color Shift 제거)

  • Park, Jun-Hee;Oh, Seung-Won;Yoon, Tae-Hoon
    • Korean Journal of Optics and Photonics
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    • v.26 no.2
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    • pp.110-114
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    • 2015
  • We propose a reflective cholesteric liquid crystal cell with reduced color shift, using dichroic dyes. Color-shifted light is absorbed by dye molecules in the proposed dye-doped cholesteric liquid crystal (DDCLC) cell. We have shown that the color shift can be reduced by increasing the concentration of dye molecules in the proposed DDCLC cell.

A Study of the Stability and Moisturizing Effect of Non-Animal Cholesteric Liquid Crystal (비동물성 콜레스테릭 액정의 안정성과 보습효능에 관한 연구)

  • Woo, Byoung Young;Min, Dae Jin;Baek, Heung Soo;Kim, Shin Hyoung;Hwang, Joon Young;Park, Young Ho;Lee, John Hwan;Shin, Song Seok
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.40 no.2
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    • pp.141-153
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    • 2014
  • This study is about the development of cholesteric liquid crystals (CLCs), which are highly applicable to cosmetics formulation. The CLCs made from non-animal origin were chosen not only because they are free of animal viruses but also because they give a sense of security to the cosmetic consumers. Three kinds of new cholesteric derivatives (CI, CC, CN) were synthesized using non-animal cholesterol [NAB cholesterol (ARCH LONZA)], which was originally made by fermentation process. To develop high applicability to cosmetics formulation, we attempted to find out the optimum compositions in which CLCs can maintain their color over a wide range of temperature. The CLCs in 41 different compositions were prepared by the combinations of three cholesteric derivatives and a visual evaluation method was employed to determine the range of temperature at which the CLCs display their color. The 205 UV-VIS spectral data obtained from 41 CLCs at various temperatures were simultaneously analyzed to investigate the critical factors affecting the characteristics of the CLCs. Results showed that A4, A5, A6 and A7 were the best compositions to cosmetics formulation. A6 composition had a great moisturizing effect by the artificial skin test ($AmoReSkin^{TM}$).

Synthesis and Properties of Cholesteric Liquid Crystalline Polymers with Isosorbide Group (아이소소바이드기를 갖는 콜레스테릭 액정고분자의 합성 및 성질)

  • Gu, Su-Jin;Yoon, Doo-Soo;Bang, Moon-Soo
    • Applied Chemistry for Engineering
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    • v.28 no.2
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    • pp.230-236
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    • 2017
  • We synthesized liquid crystalline polymers containing isosorbide group as a cholesteric derivative and methylene group for controlling the transition temperature to the liquid crystal phase. Effects of the concentration of the isosorbide group and the position of the methylene group on the properties of the liquid crystalline polymer were investigated. Among all the synthesized polymers, polymers (MnHI-x) with a methylene group in the main chain showed higher melting transition temperature and thermal stability than those (SnBI-x) with a methylene group in the side chain. All the synthesized polymers showed an enantiotropic liquid crystal phase. The polymers having 10 mol% isosorbide as a cholesteric liquid crystal phase derivative showed nematic phase, and those having 20 mol% or more isosorbide showed a cholesteric or chiral smectic phase. Thus, we can conclude that the isosorbide group plays a role as a cholesteric liquid crystal phase derivative.

Fiber optic circular polarizing mirror using polymer cholesteric liquid crystal and it's application in the mode-locked fiber laser (콜레스테릭 액정 폴리머 박막을 이용한 광섬유 원편광 거울 제작 및 이를 이용한 모드 록킹 된 광섬유 레이저)

  • 장도일;김경헌;김인선;김성태
    • Korean Journal of Optics and Photonics
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    • v.11 no.2
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    • pp.91-96
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    • 2000
  • We propose a novel in-line fiber optic circular polarizing mirror utilizing cholesteric lIquid crystal (CLC) polymer [11m for the fiber laser applications. Ions matrix representation of this device has been derived and venfied experimentally. In a Fabry-Perot cavity configuration, a CLC fiber optic rmrror has been used to achieve longitudinal mode suppression as well as to obtain passively mode~locked laser operations with 630 fs laser pulses via nonlinear polarization evoluhon.oluhon.

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Simulation of Cholesteric Liquid Crystal Color Filter by Using User-defined Coating Property of an Illumination Design Software (조명 설계 소프트웨어의 사용자 정의 코팅 기능을 사용한 콜레스테릭 액정 컬러 필터 시뮬레이션에 관한 연구)

  • Beom, Tae-Won;Cui, Hao;Lee, Hak-Suk;Yang, Jeong-Mun;Park, Jong-Rak;Yoon, Ki-Cheol;Jang, Won-Gun
    • Korean Journal of Optics and Photonics
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    • v.19 no.4
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    • pp.294-301
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    • 2008
  • We have performed modeling and simulations of optical characteristics for a cholesteric liquid crystal (CLC) color filter. Berreman's $4{\times}4$ matrix method was used for the calculation of reflectance spectra of the CLC color filter with respect to the incident angle. The results were employed as input parameters for a user-defined coating property of an illumination design software based on the ray-tracing method, LightTools. Color shift characteristics of a planar transmission-type CLC color filter were simulated using LightTools. The results were compared with the results obtained with Berreman's $4{\times}4$ matrix method. It was found that color shift characteristics of the CLC color filter could be simulated to a reasonable accuracy when the reflectance spectra with less than 5 degrees of incremental incidence-angle were used as the input data for the user-defined coating property of LightTools. We have simulated color shift characteristics of a reflection-type CLC color filter having hemi-spherical patterns. The simulation method reported in this paper has been found to be also used for a non-planar CLC color filter structure.

Thermotropic Liquid Crystalline Properties of Cholesteryloxycarbonated and (Cholesteryloxycarbonyl) alkanoated Celluloses (콜레스테릴옥시카본화 그리고 (콜레스테릴옥시카보닐)알카노화 셀룰로오스들의 열방성 액정 특성)

  • Jeong, Seung-Yong;Ma, Yung-Dae
    • Polymer(Korea)
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    • v.32 no.2
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    • pp.169-177
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    • 2008
  • The thermal and optical properties of cellulose tri(cholesteryloxy) carbonate(CCE0) and cellulose tri(cholesteryloxycarbonyl)alkanoates (CCEn, n=$2{\sim}8$, 10, the number of methylene units in the spacer) were investigated. CCE0 formed an enantiotropic cholesteric phase, whereas all the CCEn exhibited monotropic cholesteric phases. CCEn with n=$3{\sim}8$ formed cholesteric phases with left-handed helical structures whose optical pitches (${\lambda}_m's$) decrease with increasing temperature. On the other hand, CCE0 and CCEn with n=2 or 10 did not display reflection colors over the full cholesteric range, suggesting that the helical twisting power of the cholesteryl group highly depends on the length of the spacer connecting the cholesteryl group to the main chain. The thermal stability and degree of order in the mesophase and the temperature dependence of the ${\lambda}_m$ observed for CCEn highly depended on n. The results were discussed in terms of the differences in the internal plasticization, the arrangement of the side groups, and the conformation of the molecules.

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.

Infulence of Spacer and Degree of Esterification on Thermotropic Liquid Crystalline Properties of Amyloses Bearing Cholesteryl Group (스페이서와 에스터화도가 콜레스테릴 그룹을 지닌 아밀로오스들의 열방성 액정 특성에 미치는 영향)

  • Jeong, Seung-Yong;Ma, Yung-Dae
    • Polymer(Korea)
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    • v.31 no.4
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    • pp.356-367
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    • 2007
  • Three kinds of amylose derivatives such as: cholesteryloxycarbonated amyloses(CAMs) with degree of esterification(DE) ranging from 1.8 to 3, (6-cholesteryloxycarbonyl)pentanoated amyloses(PAMs) with DE ranging from 0.3 to 3, and fully cholesteryloxycarbonated PAMs(CPAMs) were synthesized, and their thermotropic liquid crystalline properties were investigated. CAMs with $DE{\geq}2.6$, PAM with DE=1.6 and all the CPAMs formed enantiotropic cholesteric phases, whereas PAM with $DE{\geq}2.2$ exhibited monotropic cholesteric phases. PAM with $DE{\geq}2.2$ and CPAMs with (6-cholesteryloxycarbonyl)pentanoyl DE (DS) more than 1.0 formed cholesteric phases with left-handed helical structures whose optical pitches (${\lambda}_{m'}s$) decrease with increasing temperature. However, the ${\lambda}_{m'}s$ of these samples decreased with increasing DS at the same temperature. On the other hand, CAMs, PAM with DE=1.6, and CPAM with DS=0.3 did not display reflection colors over the full cholesteric range, suggesting that the helicoidal twisting power of the cholesteryl group highly depends on the length of the spacer joining the cholesteryl group to the main chain and DS. The thermal stability and degree of order in the mesophase observed for the amylose derivatives highly depended on DE or DS. The results were discussed in terms of the difference ul the hydrogen bond, the internal plasticization, and the decoupling of the motion of side group with the main chain.

Synthesis and Physical Properties of Cholesteryl Biphenyl Ester Derivatives (Cholesteryl biphenyl erter계 액정의 합성 및 물성에 관한 연구)

  • Jeon, Yeong-Jae
    • Korean Journal of Materials Research
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    • v.3 no.3
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    • pp.223-229
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    • 1993
  • A homologous series of cholesteryl biphenyl ester derivatives was prepared. The thermal behaviors of compounds were studied by differential scanning calorimetry and by polarizing microscope equipped with a hot-stage. The cholesteric phase is present in all the compounds, whereas the smectic one is absent in the compounds with R = 1 and 2. The compounds possessed higher phase transitiof' temperature and wider temperature range of meso phase in comparison with known cholesteric liquid crystal phases.

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