A Simple Model for Pretilted Nematic Liquid Crystal Medium and Its Torsional Surface Coupling Strength

Sugiyama, Takashi; Kuniyasu, Seiyu; Seo, Dae Shik; Fukuro, Hiroyoshi; Kobayashi, Shunsuke

doi:10.1143/jjap.29.2045

Cited by 118 publications

(32 citation statements)

References 5 publications

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“…Some investigators have proposed that the outof-plane LC tilt angle is governed by van der Waals interactions between the LC molecules and the alkyl side chains of the polyimide. [65][66][67][68][69][70][71][72][73]95,124,125,[155][156][157][158][159][160][161][162][163][164][165][166][167][168][169][170][171]185 In contrast, other investigators have suggested that LC pretilt is determined by the polymer backbone structure but is independent of the length of the side chains. [186][187][188][189] The exact mechanism controlling the LC pretilt angle on rubbed surfaces has not yet been unambiguously elucidated.…”

Section: Pis For Liquid Crystal Alignmentmentioning

confidence: 99%

High performance polyimides for applications in microelectronics and flat panel displays

2006

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Polyimides (PIs) exhibit excellent thermal stability, mechanical, dielectric, and chemical resistance properties due to their heterocyclic imide rings and aromatic rings on the backbone. Due to these advantageous properties, PIs have found diverse applications in industry. Most PIs are insoluble because of the nature of the high chemical resistance. Thus, they are generally used as a soluble precursor polymer, which forms complexes with solvent molecules, and then finally converts to the corresponding polyimides via imidization reaction. This complexation with solvent has caused severe difficulty in the characterization of the precursor polymers. However, significant progress has recently been made on the detailed characterization of PI precursors and their imidization reaction. On the other hand, much research effort has been exerted to reduce the dielectric constant of PIs, as demanded in the microelectronics industry, through chemical modifications, as well as to develop high performance, light-emitting PIs and liquid crystal (LC) alignment layer PIs with both rubbing and rubbing-free processibility, which are desired in the flat-panel display industry. This article reviews this recent research progresses in characterizing PIs and their precursors and in developing low dielectric constant, light-emitting, and LC alignment layer PIs.

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Section: Pis For Liquid Crystal Alignmentmentioning

confidence: 99%

High performance polyimides for applications in microelectronics and flat panel displays

2006

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“…[8,9] Geometrical factors can also be responsible; for example, LC molecules align parallel to the flexible long chains of a surfactant attached to substrate surfaces perpendicularly. [10] However, the surfactant alignment is not stable because the small molecules of the surfactants gradually dissolve in the LCs. Hence side-chain polymers, in particular polyimides, are used in practice, as mentioned above.…”

mentioning

confidence: 99%

Perfluoropolymer Surface for Shock‐free Homeotropic Alignment of Smectic Liquid Crystals

et al. 2009

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“…How- 4212 J. (12) where ()m denotes the midplane tilt angle and b is a fictive extrapolation length to describe the weak tilt anchoring.…”

Section: A Freederlcksz Threshold Voltage (Analytical)mentioning

confidence: 99%

Threshold behavior and electro-optical properties of twisted nematic layers with weak anchoring in the tilt and twist angle

Hirning¹,

Funk²,

Trebin³

et al. 1991

Journal of Applied Physics

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Analytical and numerical calculations of threshold behavior and electro-optical characteristics in twisted chiral nematic layers are presented, when weak anchoring in the tilt and twist angle of the director is assumed. An analytical expression for the effective twist angle and the Freedericksz threshold voltage is derived. In cells with bistabilities, we investigate the influence of the anchoring parameters and device parameters on the width of the hysteresis. Using the 4X4-matrix formalism ofBerreman [J. Opt. Soc. Am. 62, 502 (1972)], we demonstrate the influence of the weak anchoring on the transmission-versus-voltage characteristic.

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A Simple Model for Pretilted Nematic Liquid Crystal Medium and Its Torsional Surface Coupling Strength

Cited by 118 publications

References 5 publications

High performance polyimides for applications in microelectronics and flat panel displays

High performance polyimides for applications in microelectronics and flat panel displays

Perfluoropolymer Surface for Shock‐free Homeotropic Alignment of Smectic Liquid Crystals

Threshold behavior and electro-optical properties of twisted nematic layers with weak anchoring in the tilt and twist angle

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