Compositions – Liquid crystal compositions
Patent
1995-10-05
1997-10-14
Wu, Shean C.
Compositions
Liquid crystal compositions
25229961, 25229963, 25229964, 25229965, 349 2, 349183, 349187, 5253295, 526 72, 526291, 526318, 428 1, C09K 1952, G02F 113, C08F 2000, C08F22200
Patent
active
056768788
DESCRIPTION:
BRIEF SUMMARY
This is a 35 U.S.C. .sctn. 371 national phase application of PCT/GB94/00662 filed Mar. 30, 1994.
This invention concerns novel liquid crystal polymer (LCP) materials, novel intermediates and method for preparing same.
BACKGROUND OF THE INVENTION
LCP's are known and are used in the electro-optical device industry, for example, in optical storage devices, in non-linear optical devices and in pyroelectric devices, see for example, GB 2146787 A and Makromol Chem, 186 2639-2647, 1985.
One known type of LCP consists of a polymeric backbone to which are attached laterally pendant side chains which have a chemical structure that is mesogenic, ie. that induces liquid crystalline character, these being known as side chain liquid crystal polymers. Work in this field has identified a large number of side chain structures which are suitable, see for example GB 2146787 A. For some purposes it is desirable that the LCP shows a smectic C (S.sub.c) or chiral smectic C (S.sub.c.sup..cndot.) liquid crystal phase, and a particularly preferred side chain for achieving this is one which contains a laterally fluorinated biphenyl or terphenyl system.
Side chain liquid crystal polyacrylates and polymethacrylates are known, Polymer Communications, 24 364-365, 1988; Liquid Crystals 12(2) 305-318, 1992, having a polyacrylate or polymethacrylate backbone, with dependent mesogenic side chains, ie. of general structure: ##STR2##
Where (CH.sub.2).sub.m is the spacer group, X is the mesogenic side chain and R is hydrogen in the case of polyalkylacrylates, being methyl in polymethacrylates.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a synthetic scheme for the preparation of liquid crystal polymers;
FIG. 2 illustrates a liquid crystal device; and
FIG. 3 illustrates a pyroelectric device.
SUMMARY OF THE INVENTION
According to the present invention there is provided a novel LCP material having improved liquid crystal properties over known LCP materials and which my comprise the same or different monomer units, ie. may comprise polymers or copolymers, and having a general structure (A): ##STR3## wherein X=CN, COR, CO.sub.2 R, CHO, CF.sub.3 ;
The mesogenic group my be defined from structure (B); ##STR4## wherein A, B and D are independently selected from: ##STR5## W.sub.1 and W.sub.2 are independently selected from: a single covalent bond, COO, OCO, CH.sub.2 CH.sub.2, CH.sub.2 O, OCH.sub.2, 0; derivatives, where R=chiral, straight or branched chain alkyl and includes where one or more CH.sub.2 groups can be substituted by CH(CN), CH(CF.sub.3), CH(Cl), CH(CH.sub.3), where if more than one CH.sub.2 group is substituted then such substitution is not carried out on neighbouring CH.sub.2 groups.
The copolymer my be random, block or any other variation as is known in the art.
Preferably Y may be OH and the OH groups used as a point of attachment for cross-linking agents to form elastomers, examples of such cross-linkage agents include. ##STR6##
According to another aspect of the present invention there are provided intermediate compounds, or monomer units, which, although not themselves liquid crystalline, polymerise to form LCP materials according to the present invention.
According to a further aspect of the present invention there is provided a method of producing the intermediate compounds. The method may comprise the use of the Bayliss-Hillman reaction (illustrated in Scheme 1(b)), which has not hitherto been used in liquid crystal chemistry.
The method may also comprise reactions, other than the Bayliss-Hillman reaction, to produce the intermediate compounds, as would more readily occur to one skilled in the art.
The liquid crystal polymer or copolymer may comprise intermediate compounds, or monomers, of general structure (C): ##STR7## wherein X=CN, COR, CO.sub.2 R, CHO, CF.sub.3 ;
The monomer unit my comprise any ore of the following examples 1.3a to 1.3m. ##STR8##
The monomer units may be used to synthesise polymers or copolymers of general structure (D): ##STR9## wherein X=CN, COR, CO.sub.2 R, CHO, CF.sub.3 ;
The liquid crystal pol
REFERENCES:
patent: 4983429 (1991-01-01), Takayanagi et al.
Shibaev et al. "Themotropic Liquid-Crystalline Polymers: 14. Themo-recording on Liquid-Crystalline Polymers with the Aid of a Laser Beam", Polymer Communications, vol. 24, No. 12, pp. 364-365, 1983.
Hall Alan W.
Hill Jonathan S.
Lacey David
McDonnell Damien G.
Evaluation Research Agency, DRA
The Secretary of State for Defence in Her Britannic Majesty's Go
Wu Shean C.
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