Compositions – Liquid crystal compositions – Containing nonchiral additive having no specified mesophase
Patent
1995-06-12
1998-12-01
Wu, Shean C.
Compositions
Liquid crystal compositions
Containing nonchiral additive having no specified mesophase
25229901, 349 92, 428 1, C09K 1900, G02F 11333
Patent
active
058433333
DESCRIPTION:
BRIEF SUMMARY
BRIEF DESCRIPTION OF THE INVENTION
This application is 371 of PCT/EP94/02147, on Jun. 29, 1994. A composite of one or more metallo organo moieties as part of a liquid crystal phase that is uniformly and discretely dispersed in a polymer matrix, processes for making the composite, and liquid crystal devices containing the liquid crystal mixture, and the composite.
BACKGROUND TO THE INVENTION
The nature of liquid crystal materials may be summarized as follows. The three common states of matter are the solid, liquid, and gas states in which the randomness of geometrical arrangement of the molecules increases from the solid to the liquid to the gas. The gas and the ordinary liquid are both isotropic, having the same physical properties in all directions. Most solids are found to be crystalline; that is, their molecular units are arranged in a regular repeating geometrical pattern of lattice units and consequently are frequently anisotropic in that their physical properties vary depending upon the direction of measurement with respect to different crystal axes. Certain organic solid compounds exhibit a peculiar behavior such that upon melting a turbid melt results that changes abruptly to clear isotropic liquid upon heating to a higher temperature. In this temperature range, these compounds are anisotropic with respect to all physical properties, as well as transmission of light. Thus, the characteristics of these compounds are partly those of the isotropic liquid since they exhibit liquid flow and partly those of the anisotropic solid. Therefore, these materials are often called "liquid crystals" or, more accurately, "crystalline liquids" and are sometimes classified as a fourth state of matter referred to as the mesomorphic state or mesophase, being a state or phase intermediate that of the anisotropic crystal and that of the isotropic liquid. All liquid crystals have two indices of refraction: an extraordinary index of refraction n.sub.e measured along the long axis of the liquid crystals, and a smaller ordinary index of refraction n.sub.o measured in a plane perpendicular to the long axis. The long axis of the liquid crystal defines its optic axis. There are essentially two major classes of liquid crystals, the "nematic" state and the "smectic" state. The nematic liquid crystal materials generally consist of rod-shaped molecules that tend to align parallel to a common direction resulting in anisotropy for many of the bulk properties.
When the liquid crystal alignment is "homeotropic"(perpendicular to, e.g., a supporting glass surface), a sample of the liquid crystal is optically clear (pseudo-isotropic). However, when a critical voltage is applied (typically 2 to 20 volts per mil) to the liquid crystal film, a critical current flow disrupts the uniform alignment causing scattering or refraction of incident light, termed "dynamic scattering." Dynamic scattering is one casee where the dielectric anisotropy of liquid crystals is negative (A .sup.31 <0). With "twisted nematic," with A .sup.31 >0, which is mostly used in liquid crystal display technology, the original alignment is homogeneous (parallel to the substrate surface) and is scattering in field-off and clear in field-on states. As a consequence of this scattering, the light intensity transmitted through the liquid crystal cell decreases. The smectic state is a more highly ordered state than the nematic state. The smectic state does not exhibit dynamic scattering in response to an electric field. Smectic materials of appropriate chemical structure exhibit a very low crystal-to-mesomorphic transition temperature and often may exist in a mesomorphic state at room temperatures. However, mixtures of smectic and nematic materials may be produced which are effective in dynamic scattering at room temperatures. Further, mixtures of crystalline liquids, such as cholestric liquid crystals and the like, can be used for purposes of tint or coloration. An ordinary nematic liquid crystal or smectic C phase can be converted to a cholesteric by adding an opti
REFERENCES:
patent: 4728547 (1988-03-01), Vaz et al.
patent: 4970021 (1990-11-01), Nakatsuka et al.
patent: 5087387 (1992-02-01), Mullen et al.
patent: 5124183 (1992-06-01), Nakano et al.
CAPLUS 1992: 561412, 1992.
Sniaricerche S.c.p.A
Wu Shean C.
LandOfFree
Metallo organo liquid crystals in a polymer matrix does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Metallo organo liquid crystals in a polymer matrix, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Metallo organo liquid crystals in a polymer matrix will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2392915