Anchoring of a nematic liquid crystal on a wettability gradient
We have studied the anchoring of the nematic liquid crystal 5CB (4'-n-pentyl-4-cyanobiphenyl) as a function of the surface wettability, thickness of the liquid crystal layer, and temperature by measuring the birefringence of a hybrid aligned nematic cell where the nematic material was confined...
| Publié dans: | Langmuir : the ACS journal of surfaces and colloids. - 1985. - 22(2006), 23 vom: 07. Nov., Seite 9753-9 |
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| Format: | Article |
| Langue: | English |
| Publié: |
2006
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| Accès à la collection: | Langmuir : the ACS journal of surfaces and colloids |
| Sujets: | Journal Article |
| Résumé: | We have studied the anchoring of the nematic liquid crystal 5CB (4'-n-pentyl-4-cyanobiphenyl) as a function of the surface wettability, thickness of the liquid crystal layer, and temperature by measuring the birefringence of a hybrid aligned nematic cell where the nematic material was confined between octadecyltriethoxysilane-treated glass surfaces, with one surface linearly varying in its hydrophobicity. A homeotropic-to-tilted anchoring transition was observed as a function of the lateral distance along the hydrophobicity gradient, typically in a region corresponding to a water contact angle of approximately 64 degrees. The effect of the nematic layer thickness was measured simultaneously by preparing a wedge cell where the thickness varied along the direction perpendicular to the wettability. The detailed behavior of the onset of birefringence was found to be consistent with a dual-easy-axis model that predicts a discontinuous anchoring transition from homeotropic to planar. The anchoring was independent of temperature, except within 1 degrees C of the nematic-to-isotropic transition temperature (T(NI)). As the temperature approached T(NI), the tendency for planar anchoring gradually increased relative to that for homeotropic anchoring |
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| Description: | Date Completed 07.09.2007 Date Revised 31.10.2006 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |