Cholesteric polymer network

Details Cholesteric polymer network Cholesteric polymer network

1997-05-23

2000-01-04

Kelly, C. H.

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

25229901, 25229966, 25229967, 25229965, 25229961, C09K 1930, C09K 1952, C09K 1912, C09K 1920

Patent

active

060106433

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a liquid crystalline material in the form of cholesteric polymer network, wherein the polymerized material is obtainable by copolymerization of a compound (a) having at least two polymerizable functional groups and a chiral polymerizable compound (b), characterized in that (b) is a terpenoid.
In European Patent Application EP 451 905 a liquid crystalline material in the form of an anisotropic gel comprising a polymerized liquid crystalline material is disclosed and a low-molecular nematic liquid crystalline material.
The European patent application EP 0 399 279 discloses erasable, laser-readible recording elements based on ferroelectric liquid crystalline polymers including terpenoid derivatives.
The mesogenic core of these terpenoid derivatives is linked to a polymer group with a long-chained spacer.
There is no hint to cholesteric polymer networks nor to compounds with short-chained spacers.
In accordance with the invention, a liquid crystalline material as described in the opening paragraph is obtained, wherein the polymerized material is obtainable by copolymerization of a compound (a) having at least two polymerizable functional groups and a chiral polymerizable compound (b), characterized in that (b) is a terpenoid.
Preferred embodiments of the invention are:
a) A liquid crystalline material wherein material b) is a polymerizable material comprising a structure element of the formula 1: ##STR1## in which T is a terpenoid radical.
b) A liquid crystalline material wherein the material (b) is obtainable from a chiral, polymerizable compound of the formula I ##STR2## HWN--, CH.sub.2 .dbd.CH--, CH.sub.2 .dbd.CH--O-- or HS--CH.sub.2 --(CH.sub.2).sub.m --COO-- with W being H, Cl or alkyl with 1-5 C atoms and m being 1-7, non adjacent CH.sub.2 groups to be replaced by --O--, more ring systems optionally linked by bridging groups,
c) A liquid crystalline material wherein the terpenoid radical is selected from menthyl, neomenthyl, isopinocampheyl, isolongifolyl, fenchyl, corveyl, myrthenyl, nopyl, citronellyl, dihydrocitronellyl.
d) A liquid crystalline material wherein compound (a) is a bisacrylate of formula IIa ##STR3## wherein R is H, CH.sub.3 or Cl ##STR4## with L being CH.sub.3, --COCH.sub.3, --CN, F or Cl and r being 0, 1 or 2.
e) A liquid crystalline material wherein the polymerizable material comprises at least one achiral compound having one polymerizable functional group, in particular a compound of formula III it being possible for one or more CH.sub.2 groups in these radicals to be replaced by --O--, --S--, --SO--, --OCO--, --COO-- or --O--CO--O-- in such a manner that oxygen atoms are not linked directly to one another.
f) A liquid crystalline material which is obtainable by copolymerization of at least one polymerizable compound having a short chain spacer group.
Another aspect of the invention is copolymerizable precursor materials comprising at least one bifunctional reactive achiral compound of formula II in which ##STR5## wherein W has the meaning given or in which R.sup.1 and R.sup.4 are vinylether radicals of formula CH.sub.2 .dbd.CH--O--. copolymerizable precursor materials comprising at least one chiral polymerizable compound of formula I and at least two achiral polymerizable compounds of formula III, wherein at least one compound of formula III has a short chain spacer group and one compound of formula III has a long chain spacer group, in order to suppress smectic phases. compound of formula I and at least one achiral polymerizable compound of formula IV ##STR6## P, X, R.sup.3 and u have the meaning given, R.sup.5 has the meaning given for R.sup.1,
Another aspect of the invention is:
reactive chiral compounds of formula I in which at least one aromatic ring is substituted by fluorine; reactive chiral compounds of formula I in which integer between 2 and 10; ##STR7## in which R.sup.1, P, X and u have the meaning given, and W is 1, 2 or 3, and ##STR8## in which R.sup.1, P and u have the meaning given.
The inventive compositions comprise as a rule 0.4 to 10%, in

REFERENCES:
patent: 4784793 (1988-11-01), Coates et al.
patent: 4983479 (1991-01-01), Broer et al.
patent: 5518652 (1996-05-01), Parri et al.
patent: 5705093 (1998-01-01), Coates et al.
patent: 5746940 (1998-05-01), Coates et al.
Chem. Abs. 9588, Oct. 1964.

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