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Aligning Nematic Liquid Crystals

IP.com Disclosure Number: IPCOM000074256D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Haller, I: AUTHOR [+2]

Abstract

This description relates to the preparation of relatively large uniform areas of aligned nematic liquid crystal film between transparent plates. It is known that films of nematic liquid crystals can be aligned by first rubbing with filter paper, the glass surfaces which are to enclose the liquid crystal film. The term alignment signifies that the molecules of the liquid crystal become oriented in the direction in which the surfaces have been rubbed to form the equivalent of a slab of a positive uniaxial crystal with the optic axis lying in the rubbing direction. It is also known, however, that the alignment obtained with the above-mentioned method is generally unsatisfactory, i.e.

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Aligning Nematic Liquid Crystals

This description relates to the preparation of relatively large uniform areas of aligned nematic liquid crystal film between transparent plates. It is known that films of nematic liquid crystals can be aligned by first rubbing with filter paper, the glass surfaces which are to enclose the liquid crystal film. The term alignment signifies that the molecules of the liquid crystal become oriented in the direction in which the surfaces have been rubbed to form the equivalent of a slab of a positive uniaxial crystal with the optic axis lying in the rubbing direction. It is also known, however, that the alignment obtained with the above-mentioned method is generally unsatisfactory, i.e., streaks and spots of various sizes appear in which the orientation does not conform to the direction of rubbing and uniformity over large areas is poor.

In this process, the glass surfaces are treated with a material such as 2-p- octylphenoxyethanol before rubbing. Thereby, the imperfections in the subsequent alignment of liquid crystals are largely eliminated. The materials that are suitable should have the following characteristics. 1) They should be amphiphilic, i.e., their molecules should contain both a polar portion to facilitate adsorption to the polar glass surface and an aromatic portion to provide affinity to the liquid crystal. 2) Their molecules should have an elongated shape. A few drops of 2-p-octylphenoxyethanol are placed on 1" by 3" gla...