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Chemical Physics Publications

1992

Articles 1 - 4 of 4

Full-Text Articles in Physics

Cholesteric Liquid-Crystal Polymer Dispersion For Haze-Free Light Shutters, Deng-Ke Yang, Liang-Chy Chien, J. W. Donae Jun 1992

Cholesteric Liquid-Crystal Polymer Dispersion For Haze-Free Light Shutters, Deng-Ke Yang, Liang-Chy Chien, J. W. Donae

Chemical Physics Publications

A new dispersion involving a polymer in low concentration with a cholesteric liquid crystal is reported. Two types of light modulators from these materials are described as a normal mode shutter which is opaque (light scattering) in the field-OFF state and transparent in the field-ON state and a reverse-mode shutter with the opposite field conditions. The transparent state of both cells is haze-free for all viewing angles making the material attractive for window applications and direct view displays.


Method To Obtain Uniform Bookshelf Textures In Smectic C-Asterisk Liquid-Crystals, Antal Jakli, A. Saupe May 1992

Method To Obtain Uniform Bookshelf Textures In Smectic C-Asterisk Liquid-Crystals, Antal Jakli, A. Saupe

Chemical Physics Publications

A new method is described to obtain homogeneous bookshelf textures in thin films of ferroelectric smectic C* material with short pitch and high P(s). The surfaces were coated with silane to obtain a homeotropic texture. The sample was realigned to a homogeneous bookshelf texture under simultaneous application of an electric field and shearing. The texture is stable and gives a very good contrast (approximately 80) under permanent drive condition.


Spontaneous Transition From Chevron To Striped Texture Of A Planar Smectic-C-Asterisk Liquid-Crystal, Antal Jakli, A. Saupe Apr 1992

Spontaneous Transition From Chevron To Striped Texture Of A Planar Smectic-C-Asterisk Liquid-Crystal, Antal Jakli, A. Saupe

Chemical Physics Publications

We observed a spontaneous transition from a vertical chevron texture to a striped texture (striped "bookshelf" texture) in a surface-stabilized film of ferroelectric liquid crystal mixture (ZLI 4237-000, from E. Merck). The transition takes place gradually, at temperatures more than 20-degrees-C below the smectic-A-smectic-C* transition. The layers in the stripe texture are perpendicular to the plate, but in successive stripes, the orientation of the layer normal alternates by +/- 23-degrees. The polarization is perpendicular to the film and alternates between up and down, while the director orientation is in plane and alternates by +/- 5-degrees. The width of the stripes was typically ...


Effect Of A Polymer Network On The Alignment And The Rotational Viscosity Of A Nematic Liquid-Crystal, Antal Jákli, D. R. Kim, Liang-Chy Chien, A. Saupe Jan 1992

Effect Of A Polymer Network On The Alignment And The Rotational Viscosity Of A Nematic Liquid-Crystal, Antal Jákli, D. R. Kim, Liang-Chy Chien, A. Saupe

Chemical Physics Publications

Polymer dispersions were made by photoinduced polymerization of 4,4'-bisacryloyl-biphenyl in liquid crystal 4-4'-cyano pentyl biphenyl as nematic solvent. Samples were prepared with 0.5, 1, and 1.5 wt % monomer. The polymerization was done in the isotropic phase. The rotational viscosities of the two lower concentration samples increased only moderately after UV curing (3 mW/cm2, 25 min). The 1.5 wt % sample gave under the same condition a nematic with a fairly rigid anisotropic network that did not realign in magnetic field up to 20 kG. We estimate that the mesh size of the network was ...