• Title/Summary/Keyword: 액정구조

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Preparation of Optically Anisotropic Film by Sunset Yellow Chromonic Liquid Crystal (Sunset Yellow 액정 색소를 이용한 광학적 이방성 필름 제조)

  • Kim, Byungchul;Chang, Eugene;Shin, Seunghan
    • Applied Chemistry for Engineering
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    • v.22 no.1
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    • pp.81-86
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    • 2011

  • The aqueous solution of Sunset Yellow-FCF (SY-FCF) began to show schlieren texture at room temperature when its concentration reaches 25 wt%. A further increase of the concentration of SY-FCF to 28 wt% resulted in a perfect nematic liquid crystal phase. However, more than 30 wt% of SY-FCF in aqueous solution was required to make an optically anisotropic film simply by shear coating. In our study, concentration of SY-FCF solution, coating speed, drying temperature, and relative humidity were considered as coating parameters affecting the preparation of optically anisotropic thin films. From analysis of variance analysis (ANOVA), the solution concentration was revealed as a main factor affecting the film thickness. The drying temperature and solution concentration were main factors affecting the transmittance of parallel direction ($T_o$). Especially, SY-FCF aqueous solution with high concentration induced a better alignment of LC columns and produced highly oriented anisotropic films. In this study, optically anisotropic films prepared by 33 wt% of SY-FCF in aqueous solution showed 89.7~98.7% of degree of polarization.

  • https://doi.org/10.14478/ace.2011.22.1.081 인용 PDF KSCI

Thermotropic Liquid Crystalline Behavior of Poly[1-{4-(4'-cyanophenylazo)phenoxyalkyloxy}ethylene]s (폴리[1-{4-{4'-시아노페닐아조)펜옥시알킬옥시}에틸렌]들의 열방성 액정 거동)

  • Jeong, Seung-Yong;Lee, Jae-Yoon;Ma, Yung-Dae
    • Polymer(Korea)
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    • v.33 no.4
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    • pp.297-306
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    • 2009

  • A homologous series of side chain liquid crystalline polymers, poly [1-{4-(4'-cyanophenylazo)phenoxyalkyloxy}ethylene]s(CAPETn, where n, the number of methylene units in the spacer, is $2{\sim}10$) were synthesized from poly(vinyl alcohol) and 1-{4-(4'-cyanophenylazo)phenoxy}alkylbromides(CAPBn, n=$2{\sim}10$), and their thermotropic liquid crystalline phase behaviors were investigated. The CAPBn with n of $2{\sim}5$ did not show any liquid crystalline behavior, while those with n of 6 and $7{\sim}10$ showed enantiotropic and monotropic nematic phases, respectively. In contrast, among the CAPETn polymers, only CAPET5 exhibited an enantiotropic nematic phase, while other polymers showed monotropic nematic phases. The isotropic-nematic transition temperatures of CAPETns and their entropy variation at the phase transition that were higher values than those of CAPBns, demonstrated a typical odd-even effect as a function of n. These phase transition behaviors were disscussed in terms of the 'virtual trimer model' by Imrie. The mesophase properties of CAPETns were largely different from those reported for the polymers in which the (cyanophenylazo) phenoxy groups are attached to polyacrylate, polymethacrylate, and polystyrene backbones through polymethylene spacers. The results indicate that the mode of chemical linkage of the side group with the main chain plays an important role in the formation, stabilization, and type of mesophase.

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