• Title/Summary/Keyword: 액정구조

Search Result 226, Processing Time 0.023 seconds

Pitch Variations in Cholesteric Liquid Crystals by Phase Separation (상 분리에 의한 콜레스테릭 액정의 피치 변화)

  • Park Han-Soo;Kim Beom-Kyung;Kim Whan-Ki;Kim In-Sun;Song Ki-Gook
    • Polymer(Korea)
    • /
    • v.30 no.2
    • /
    • pp.182-186
    • /
    • 2006
  • Due to their periodic helical structure, cholesteric liquid crystals (CLC) have a unique ability to selectively reflect light. CLC films reflecting a broad wavelength band were prepared by inducing a pitch gradient in CLC layer through a phase separation. The reflection bandwidth of the CLC cell was broaden as irradiation light intensity decreased and as the amount of the UV absorbing dye increased. Initial reflection bandwidth of 50 nm was broaden to 300 nm Various pitch distributions in the CLC cell was observed using SEM and ATR-IR technique was used to prove that the pitch distributions are induced through the phase separation.

Characteristic Analysis of Spacial Electric Field Distribution in Liquid Crystal of TFT-LCD Panel (3차원 유한요소법을 이용한 TFT-LCD 액정에서의 공간 전기장 분포 특성 분석)

  • Jung, Sang-Sik;Kim, Nam-Kyung;Kim, Dong-Hun;Noh, Min-Ho;Lee, Kyu-Sang
    • Journal of the Korean Magnetics Society
    • /
    • v.22 no.3
    • /
    • pp.91-96
    • /
    • 2012
  • In this paper, a three-dimensional finite element model based on the multi-pixel was constructed to accurately predict electric field distributions including an interference phenomenon between adjacent pixels in the liquid crystal of a complicated TFT-LCD panel. Utilizing the elaborate numerical model, the characteristics of spatial electric field distributions depending on various fault-electrode conditions are thoroughly examined on the basis of the field distribution of a normal electrode condition. The validity of the proposed model is proved by comparing the simulation results with those of the existing optical inspection equipments.

Synthesis and Characterization of New Thermotropic Liquid Crystalline Polyurethanes (새로운 형태의 액정폴리우레탄의 합성 및 특성)

  • Lee, Jong-Baek;Lee, Kwang-Hyun;Kang, Byung-Chul
    • Elastomers and Composites
    • /
    • v.41 no.2
    • /
    • pp.108-115
    • /
    • 2006
  • A series of thermotropic polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, 1,4-phenylene diisocyanate, and hexamethylene diisocyanate with 4,4'-Bis(9-hydroxynonoxy)biphenyl (BP9). 4,4'-bis(9-hydroxynonoxy)biphenyl exhibited a smectic type mesophase. Mesophase was found for all synthesized liquid crystalline polyurethanes except 1,4-PDI/BP9 based polyurethane. Structures of the monomer and the corresponding polymers were identified using FT-IR and $^1H-NMR$ spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry and optical polarizing microscopy.

Synthesis and Characterization of Thermotropic Liquid Crystalline Polyurethanes (액정폴리우레탄의 합성 및 특성)

  • Lee, Jong-Back;Lee, Kwang-Hyun;Kang, Byung-Chul;Lee, Dong-Jin
    • Elastomers and Composites
    • /
    • v.44 no.3
    • /
    • pp.329-335
    • /
    • 2009
  • Four series of novel liquid crystalline polyurethanes were synthesized by the polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate (2,6-TDI), 2,5-tolylene diisocyanate (2,5-TDI), 2,4-tolylene diisocyanate (2,4-TDI), and 1,4-phenylene diisocyanate (1,4-PDI) with 4,4'-bis(5-hydroxypentoxy)biphenyl (BP5). 4,4'-bis(5-hydroxypentoxy)biphenyl exhibited a smectic type mesophase. Mesophase was found for all synthesized liquid crystalline polyurethanes except 1,4-PDI/BP5. The structures and the thermal properties of polyurethanes were studied by using FT-IR and ^1H$ NMR spectroscopy, DSC measurements and a polarizing microscope equipped with a heating stage.

Orientation of Evaporated Pentacene Molecules on Rubbed Polyvinylcinnamate Film (러빙한 Polyvinylcinnamate 필름 위에 종착된 Pentacene 분자의 배향)

  • Park, Sun-Hee;Song, Ki-Gook
    • Polymer(Korea)
    • /
    • v.32 no.3
    • /
    • pp.290-294
    • /
    • 2008
  • Induction mechanism of molecular orientations for a rubbed polymer film as an alignment layer was investigated using polarized UV/Vis spectroscopic experiments for polyimide and polyvinylcinnamate whose conjugated electrons are located along main chain and side chain, respectively. By determining anisotropy formed in the rubbed film, LC director formed in the LC cell, and orientation direction of deposited pentacene molecules, it was found that LC orientation was induced mainly by molecular interactions whereas surface microgrooves formed by the rubbing process affect the orientation direction of deposited pentacene molecules.

Optimal Surfactant Structures for Cosurfactant-Free Microemulsion Systems (II) -Dialkylbenzene and Dialkylphenol Hydrophobes- (계면활성제의 구조가 Microemulsion 형성에 미치는 영향(제II보) -친유기 Dialkylbenzene과 Dialkylphenol-)

  • 김천희
    • Journal of the Korean Society of Clothing and Textiles
    • /
    • v.18 no.3
    • /
    • pp.419-428
    • /
    • 1994
  • Microemulsion을 형성하기 위해서는 일반적으로 주계면활성제와 함께 보조계면황성제가 첨가 된다. 그러나 보조계면활성제는 이론적으로 반드시 필요한 것은 아니며, 주계면활성제의 친유기 구조를 적절히 변화시킴으로써 보조계면황성제의 필요량을 감소시킬 수 있다. Microemulsion계 를 형성하기 위한 최적의 계면황성제구조를 찾기 위하여 twin tail형 계면활성제인 dialkylbenzene과 dialkylphenol친유기를 갖는 계면황성제를 연구하였다. p-dihexylbenzene sodium sulfonate는 보조계면활성제 없이 microemulsion을 형성하였지만, dialkylphenol sodium sulfates는 젤이나 액정등을 제거하기 위하여 보조계면활성제를 필요로 하였다.

  • PDF

Synthesis and Characterization of Wholly Aromatic Polyester Liquid Crystalline Thermosets (전방향족 폴리에스터 열경화성 액정의 합성과 특성)

  • Moon, Hyun-Gon;Jung, Myung-Sup;Chang, Jin-Hae
    • Polymer(Korea)
    • /
    • v.36 no.1
    • /
    • pp.9-15
    • /
    • 2012
  • We prepared a series of aromatic liquid crystals (LCs) based on wholly aromatic ester units with the reactive end group methyl maleimide by means of melt condensation method, and the resulting LCs were thermally crosslinked to produce liquid crystalline thermoset (LCT) films. The synthesized LCs and LCTs were characterized with Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), and polarizing optical microscopy (POM) with a hot stage. The glass transition temperature ($T_g$) and coefficient of thermal expansion are strongly affected by the mesogen units in their main chain structures. The $p$-substituted biphenyl LC was found to have the highest thermal property value.

Thermotropic Polyurethanes Prepared from Diisocyanates and 4,4'-Bis(3-hydroxypropoxy)Biphenyl Containing Mesogenic Unit (4,4'-Bis(3-hydroxypropoxy)Biphenyl와 Diisocyanate 에 의한 열방성 액정폴리우레탄 합성)

  • Lee, Jong Baek
    • Korean Chemical Engineering Research
    • /
    • v.48 no.5
    • /
    • pp.615-620
    • /
    • 2010
  • In this study, five series of novel polyurethanes was synthesized by the polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate(2,6-TDI), 2,5-tolylene diisocyanate(2,5-TDI), 2,4-tolylene diisocyanate(2,4-TDI), and 1,4-phenylene diisocyanate(1,4-PDI), hexamethylene diisocyanate(HDI) with 4,4'-Bis(3-hydroxypropoxy)biphenyl (BP3), 4,4'-bis(3-hydroxypropoxy)biphenyl exhibited a smectic type mesophase. Monotropic mesophase was found for all synthesized liquid crystalline polyurethanes except HDI/BP3. In contrast, 1,4-PDI/BP3 without a methyl substituent in the phenylene unit exhibited no explicit mesomorphic behavior, which was confirmed by DSC and polarizing microscopy experiments. Structures of the compound were identified by FT-IR and $^1H$-NMR spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry(DSC), polarized optical microscopy(POM) and x-ray diffraction analysis.

Effects of Alkoxy Side Chain on the Properties of Wholly Aromatic Liquid Crystalline Polyesters with Biphenylene Units (알콕시 곁사슬기가 비페닐렌구조를 갖는 전방향족 액정폴리에스터의 물성에 미치는 영향)

  • Lee, Eung-Jae;Bang, Moon-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.11 no.10
    • /
    • pp.4041-4046
    • /
    • 2010
  • Wholly aromatic polyesters having flexible alkoxy side chain were synthesized by direct polycondensation. The synthetic polymers have been characterized by $^1H$-NMR, FT-IR. DSC, TGA, optical polarizing microscope and X-ray diffractometer. The inherent viscosities (${\eta}_{inh}$) measured in 1,1,2,2-tetrachloroethane (TCE) were 0.46~2.41 dL/g. The polymers having side chain showed double melting transition, ie, solid-sanidic liquid crystalline (LC) phase transition ($T_{m1}$) and sanidic LC phase-nematic LC phase transition ($T_{m2}$). As incresing length of alkoxy side chain, phase transition temperatures decreased and solubilities in organic solvents incresed. The peaks of $2{\theta}\;{\simeq}5$ and $2{\theta}\;{\simeq}20$ in X-ray diffractograms are due to crystallization of polymer main chain and of long side chain, respectively.

Synthesis and Properties of Semi-flexible Liquid Crystalline Polyesters with Rigid Lateral Group (강직한 측쇄기를 갖는 반 유연성 액정폴리에스터의 합성 및 성질)

  • Park, Jong-Ryul;Lee, Eung-Jae;Yoon, Doo-Soo;Bang, Moon-Soo;Choi, Jae-Kon
    • Elastomers and Composites
    • /
    • v.48 no.4
    • /
    • pp.306-311
    • /
    • 2013
  • A series of liquid crystalline polyesters containing the 4-chloro benzoate group on the hydroquinone unit of rigid group were synthesized through solution polymerization of 2,5-di(4-chlorobenzoate)hydroquinones and 4,4'-dicarboxy-${\alpha},{\omega}$-diphenoxy alkane. The structure and properties for synthesized polymers were investigated by $^1H$-NMR, FT-IR, DSC, TGA, and POM. As result of investigations, The presence of the methylene group and bulky lateral groups in polymer chain have a great influence on the properties of polymers such as solubilities and thermal transitions. The optical textures of polymers revealed a weak birefringence in the melt and indicated that they form nematic mesophase. All polymers have very narrow mesophase temperature ranges.