• Title/Summary/Keyword: cholesteric pitch gradient

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Syntheses and Optical Properties of Cholesteric Liquid Crystal Polymers Utilizing p-Phenylene Bis-(p-(3-acryloxy-2-methylpropyloxy)benzoate

  • Yoon, Ung-Chan;Choi, Jung-Hei;Jin, Sung-Ho;Song, Dong-Mi
    • Journal of Photoscience
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    • v.12 no.1
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    • pp.41-46
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    • 2005
  • We synthesized chiral choleseric liquid crystalline monomer p-phenylene bis-(p-3-acryloxy-2(S)-methylpropoxy)benzoate (1) and achiral nematic liquid crystalline monomer, p-phenylene p-acryloxy-6-hexyloxy-p-octyloxybenzoate (2) for the construction of cholesteric polymer network with a pitch gradient. In this research we attempted to synthesize cholesteric polymer film which have a wide reflection bandwidth in the region of visible wavelength with the synthesized chiral cholesteric monomer 1 and nematic monomer 2 under various photopoly merization conditions. We succeeded to construct cholesteric polymer film network with a pitch gradient covering more than 200 nm bandwidth in the visible wavelength by diffusion controlled photostructuring method.

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Pitch Variations in Cholesteric Liquid Crystal Film by Molecular Diffusion (분자 확산에 의한 콜레스테릭 액정 필름의 피치 변화)

  • Kwon Young-Jin;Lee Won-Ju;Kim Beom-Kyung;Kim In-Sun;Song Ki-Gook
    • Polymer(Korea)
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    • v.30 no.5
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    • pp.422-425
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    • 2006
  • Due to their periodic helical structure, cholesteric liquid crystals (CLC) have a unique ability to selectively reflect visible light. CLC films reflecting a broad wavelength band were prepared by inducing a pitch gradient in CLC layers through a diffusion of small molecules and through a thermal mixing of cyclic siloxane CLC molecules with different pitch lengths. Various pitch gradients in the CLC cell were observed using UV/Vis spectrometer and SEM technique.

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)
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    • v.30 no.2
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    • pp.182-186
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    • 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.