A New Method for Inducing Homeotropic and Tilted Alignments of Nematic Liquid Crystals on Silica Surfaces

Miller, L. J.; Grinberg, J.; Myer, Gary; Smythe, D. S.; Smith, W. H.

doi:10.1007/978-1-4615-8888-7_33

Cited by 5 publications

(1 citation statement)

References 11 publications

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“…Because of this, it is widely used for liquid crystal displays such as information display devices, large-area LCD TVs, and digital displays in medical devices. One of the most widely used techniques for vertical alignment is surface treatment using silanes or long alkyl side chain alcohols as homeotropic coupling agents. , It is the steric hindrance from these protruding molecules that gives rise to the vertical alignment. Another technique is the oblique evaporation of silicon monoxides .…”

Section: Introductionmentioning

confidence: 99%

Vertical Alignment of Liquid Crystals with Negative Dielectric Anisotropy on an Inorganic Thin Film with a Hydrophilic Surface

Hwang

Ahn²,

Rho

et al. 2009

Langmuir

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The vertical alignment of liquid crystals having negative dielectric anisotropy on an amorphous silicon oxide (a-SiO(x)) thin film is the consequence of the anisotropic interaction between liquid crystals and a-SiO(x) thin films. To investigate the mechanism of the vertical alignment, we changed the physicochemical characteristics of alignment layers by controlling the composition, since the anisotropic interaction depends on the nature of both liquid crystals and an alignment layer. The variation of composition gives rise to a change in the polarizability, which is a simple measure of induced-dipole strength at the surface of the alignment layer. There is a critical transition point from planar to vertical alignment of liquid crystals, and it is the long-range van der Waals interaction that is responsible for the vertical alignment. The competition between long-range van der Waals interaction and short-range dipolar interaction were investigated and analyzed in terms of the interfacial energy between liquid crystals and an alignment layer.

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Section: Introductionmentioning

confidence: 99%

Vertical Alignment of Liquid Crystals with Negative Dielectric Anisotropy on an Inorganic Thin Film with a Hydrophilic Surface

Hwang

Ahn²,

Rho

et al. 2009

Langmuir

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Effects of Molecular Length on Nematic Mixtures

Margerum

Jensen

Lackner

1981

Molecular Crystals and Liquid Crystals

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Effects of Molecular Length on Nematic Mixtures

Margerum

Wong

Lackner

et al. 1981

Molecular Crystals and Liquid Crystals

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The properties of nematic liquid-crystal mixtures of 6alkoxyphenyl frans-4-alkylcyclohexanecarboxylates are studied as a function of temperature and their av_erage molecular length (L).Mixturesareprepared with clearpoints near 72°C(f30C)and with L varying between21.2Oand 26.15 A. At 25°C. their flow viscosity increases exponentially (from 16.3 t o 50.6 cP) as L increases. The conductivity anisotropy ( U ,~/ U J also vanes tremendously, decreasing from 1.62 to 0.49 as L increases, when compared at 25°C with tetrabutylammonium tetraphenylboride as dopant. The low values of ol /eland its temperature dependence indicate that cybotatic nematic characteristics occur when the average total number of alkyl carbons from both end groups is 8.5 or more. Short range smectic effects are dominant in the longer mixtures. All of the mi_xtures have a negative dielectricanisotropy, which linearly becomes I_ess negative with increasing L. At 25°C. dynamic scattering (DS) is observed only in the shorter L mixtures (where oll/ol > I), and the DS decay timesare relativelyfast. Comparisonsare made with similar studies onp-alkoxyphenyl p-alkylbenzoate mixtures.

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A New Method for Inducing Homeotropic and Tilted Alignments of Nematic Liquid Crystals on Silica Surfaces

Cited by 5 publications

References 11 publications

Vertical Alignment of Liquid Crystals with Negative Dielectric Anisotropy on an Inorganic Thin Film with a Hydrophilic Surface

Vertical Alignment of Liquid Crystals with Negative Dielectric Anisotropy on an Inorganic Thin Film with a Hydrophilic Surface

Effects of Molecular Length on Nematic Mixtures

Effects of Molecular Length on Nematic Mixtures

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