• Title/Summary/Keyword: polyimide(PI)

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Electro-optical Characteristics on the Rubbing-aligned Flexible Liquid Crystal Display (러빙처리된 플렉시블 액정표시소자의 전기광학특성)

  • 남기형;황정연;김종환;서대식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.8
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    • pp.866-870
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    • 2004
  • We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles on thin plastic substrates generated higher than that on glass substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer substrate are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on g1ass.

Pretilt Angle Generation and EO Performance in MLC with Polarized UV Light Irradiation Polyimide surface (폴리이미드막 표면에 직선 편광된 UV광 조사에 의한 프리틸트각 발생과 전기광학특성)

  • 서대식;이정호;이창훈
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.878-884
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    • 1998
  • We have investigated that the monodomain alignment of nematic liquid crystal (NLC) is obtained with polarized ultraviolet(PUV) light irradiation on polyimide (PI) surface. The LC alignment capability increases with increasing the UV light irradiation time. The polarized UV light irradiation on oblique angle of 60。 irradiated on PI surface rotated by 90。 at 10 min. after being normally irradiated on PI surface at 30 min., the generated pretilt angle of NLC is about 2.5。. The pretilt angle of NLC is attributed to the interaction between the LC molecules and the asymmetric triangular structure of polymer surface due to photo-depolymerization of polymer with the oblique UV light on PI surface. The voltage -transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time 60 min. were almost same in comparison with the rubbing-treated TN-LCD.

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Electro-Optical characteristics on the rubbing-aligned plastic Twisted Nematic cell (플라스틱 러빙처리된 TN셀의 전기광학 특성)

  • Nam, Ki-Hyung;Hwang, Jeoung-Yeon;Kim, Jong-Hwan;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.04a
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    • pp.18-22
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    • 2004
  • We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using thin plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles generated are about $3^{\circ}$ by the rubbing alignment method on thin plastic substrates, However, the pretilt angle are at about $1.7^{\circ}$ lower on the glass substrate than on thin plastic substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on glass.

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Electro-Optical Characteristics on the flexible substrate using the Rubbing method (플렉시블 기판에 러빙법을 이용한 전기광학특성)

  • Lee, Whee-Won;Choi, Sung-Ho;Hwang, Jeoung-Yeon;Kang, Hyung-Ku;Bae, Yu-Han;Moon, Hyun-Chan;Kim, Jong-Hwan;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.487-488
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    • 2005
  • We have investigated the Electro-Optical Characteristics for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on glass.

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Ellipsometric Characterization of Rubbed Polyimide Alignment Layer in Relation with Distribution of Liquid Crystal Molecules in Twisted Nematic Cell

  • Cho, Sung Yong;Park, Sang Uk;Yang, Sung Mo;Kim, Sang Youl
    • Current Optics and Photonics
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    • v.2 no.2
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    • pp.185-194
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    • 2018
  • Ultra-small optical anisotropy of a rubbed polyimide (PI) alignment layer is quantitatively characterized using the improved reflection ellipsometer. Twisted nematic (TN) cells are fabricated using the rubbed PIs of known surface anisotropy as alignment layers. Distribution of liquid crystal (LC) molecules in the TN cell is characterized using transmission ellipsometry. The retardation of the rubbed PI surface increases as rubbing strength increases. The tilt angle of the optic axis of the rubbed PI surface decreases as rubbing strength especially as the angular speed of the rubbing roller increases. Pretilt angle of LC molecules in the TN cell shows strong correlation with tilt angle of the optic axis of the rubbed PI surface. Both the apparent order parameter and the effective twist angle of the LC molecules in the TN cell decrease as the pretilt angle of LC molecules increases.

Ion Beam-based Surface Modification of Polyimide Films for Adhesion Improvement with Deposited Metal Layer

  • Cho, Hwang-Woo;Jung, Chan-Hee;Hwang, In-Tae;Choi, Jae-Hak;Nho, Young-Chang
    • Journal of Radiation Industry
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    • v.4 no.4
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    • pp.335-339
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    • 2010
  • In this study, the surface of polyimide (PI) films was modified using ion implantation to enhance its adhesion to a deposited copper (Cu) layer. The surfaces of the PI films were implanted with 150 keV $Xe^+$ ions at fluences varying from $1{\times}10^{14}$ to $1{\time}10^{16}ions\;cm^{-2}$. The Cu layers were then deposited on the implanted PI. The surface properties of the implanted PI film were investigated based on the contact angle measurements, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Furthermore, the adhesive strength between the deposited Cu layer and PI film was estimated through a scratch test using a nanoindenter. As a result, the surface environment of the PI film was changed by the ion implantation, which could have a significant effect on the adhesion between the deposited Cu layer and the PI.

Mechanism of Orientation of Liquid Crystal Molecules for Polarized UV-exposed Polyimide Alignment Layers (폴리애미드 배향막의 편광 자외선 조사에 따른 액정 배향 메카니즘)

  • 김일형;김욱수;하기룡
    • Polymer(Korea)
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    • v.26 no.2
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    • pp.209-217
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    • 2002
  • We studied the mechanism of orientation of polyimide molecules which were irradiated by polarized UU (PUV) using polarized Fourier transform infrared (FT-IR) spectroscopy and ultraviolet (UV) spectroscopy, According to the measured UV spectra, we found PI films mainly absorb UV light less than 350 nm wavelength, therefore, UV light less than 360 nm induces photochemical reaction of PI. PUV irradiation of PI films caused decrease of all peak intensities in the FT-IR spectra. except the newly formed broad peak at $3244 cm^{-1}$, due to degradation of the PI molecules. The remaining PI molecules after photo-degradation showed predominantly perpendicular molecular orientation to the irradiated PUV polarization direction, due to the preferential degradation of PI molecules parallel to irradiated PUV polarization direction. However the rubbing of PI films induced reorientation of the PI molecules parallel to the rubbing direction. We also investigated the alignment of the liquid crystal by rubbing or PUV irradiation. Liquid crystals align perpendicular to the PUV polarization direction and parallel to the rubbing direction.

Gas Separation Properties of Polyaniline/Polyimide Blend Membranes (Polyaniline/Polyimide 혼합막의 기체 분리 특성)

  • Lee, Ki-Seob;Kim, Jin-Hwan
    • Applied Chemistry for Engineering
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    • v.18 no.5
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    • pp.483-489
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    • 2007
  • Polyaniline (PANI)/Polyimide (PI) membranes were prepared and the effects of PANI contents and doping on the structural properties and gas separation properties were studied. The polyamic acid (PAA) solution was prepared by the polycondensation reaction of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 4,4'-oxydianiline (ODA) in 1-methyl-2-pyrrolydinone (NMP) solvent. The PANI/PI blends were obtained by mixing PAA solution and PANI solution, and were doped with 1 M aqueous HCl solution for 24 h. The structural characterizations of the as-cast and doped membranes were examined by FT-IR, XRD, and TGA. The gas permeation experiments with $H_2$, $CO_2$, $O_2$, $N_2$, and $CH_4$ were carried out by variable pressure method at $30^{\circ}C$ and 5 atm. For all gases tested, the permeability coefficients of the blends decreased with increasing PANI content and the magnitude of permeability was in the order of $H_2$ > $CO_2$ > $O_2$ > $N_2$ > $CH_4$. The permeability for PANI/PI membranes decreased after the doping process while the permselectivity increased. For $H_2/CH_4$ separation, the doped PANI/PI (75/25) membrane has a permselectivity of 991.

Electro-optical Characteristics of in the Vertical-Alignment 1/4$\pi$ Cell Using Homeotroopic Photopolymer (수직 광폴리머를 이용한 VA-1/4$\pi$셀의 전기 광학 특성)

  • 황정연;서대식;김재형
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.8
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    • pp.670-674
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    • 2001
  • The electro-optical (EO) performance in the vertical-alignment (VA) - 1/4$\pi$ cell photoaligned with polarized UV exposure on a homeotropic photopolymer surfaces was investigated. Excellent voltage-transmittance curve in the VA - 1/4$\pi$ cell photoaligned with polarized UV exposure for 3 min on the photopolymer containing cholesteryl group of 8% can be achieved. The V-T characteristics in the VA-1/4$\pi$ cell photoaligned on the photopolymer surface can be improved by increasing cholesteryl group. For response time measurement, the transmittance characteristics of the VA-1/4$\pi$ cell photopolymer surface was better than that of the VA-1/4$\pi$ cell rubbingaligned on a polyimide(PI) surface.

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Electro-optical Characteristics in the Vortical-Alignment 1/4$\pi$ Cell by photoalignment Method (광배향법을 이용한 VA-l/4$\pi$셀의 전기 광학 특성)

  • 이윤건;황정연;서대식;김재형
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.369-372
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    • 2001
  • We studied the electro-optical (EO) performance in the vertical-alignment (VA) - l/4$\pi$ cell photoaligned with polarized UV exposure on a homeotropic photopolymer surfaces. Excellent voltage-transmittance curve in the VA - l/4$\pi$ cell photoaligned with polarized UV exposure for 3 min on the photopolymer containing cholesterol group of 8% can be achieved. The V-T characteristics in the VA-l/4$\pi$ cell photoaligned on the photopolymer surface can be improved by increasing cholesteryl group. For response time measurement, the transmittance characteristics of the VA-l/4$\pi$ cell photoaligned on the photopolymer surface was better than that of the VA-l/4$\pi$ cell rubbingaligned on a polyimide(Pl) surface.

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