Mesogenic compound, liquid-crystal medium and liquid crystal display

Abstract

Mesogenic compounds of formula I-Z ##STR00001##
are suitable for use in mesogenic media. Such mesogenic media can exhibit a blue phase and comprise component A, consisting of one or more compounds of formula I-Z, and, optionally a component B, consisting of one or more compounds selected from the group of compounds of formulae
I-M and I-U, ##STR00002##
wherein the parameters are as defined herein. The media can also be stabilized by a polymer. The media can be used in electro-optical light modulation elements and displays.

Claims

1. A mesogenic compound of formula I-Z ##STR00205## wherein R.sup.1 is n-alkyl or n-alkoxy with 1 to 9 C-atoms, or alkenyl, alkenyloxy or alkoxyalkyl with 2 to 9 C-atoms, L.sup.1 is H or F, and X.sup.1 is F or CF.sub.3.

2. A mesogenic medium exhibiting a blue phase, comprising a component A, consisting of one or more compounds of formula I-Z ##STR00206## wherein R.sup.1 is n-alkyl or n-alkoxy with 1 to 9 C-atoms, or alkenyl, alkenyloxy or alkoxyalkyl with 2 to 9 C-atoms, L.sup.1 is H or F, and X.sup.1 is F or CF.sub.3.

3. The mesogenic medium according to claim 2, further comprising one or more chiral dopants.

4. The mesogenic medium according to claim 2, further comprising a second component, component B, consisting of one or more compounds selected from formulae I-M and I-U ##STR00207## wherein R.sup.1 is alkyl with 1 to 9 C-atoms, which is straight chain or branched, unsubstituted, mono- or poly-substituted by F, Cl or CN, and in which one or more CH.sub.2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NR.sup.01—, —SiR.sup.01R.sup.02—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CY.sup.01═CY.sup.02— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, Y.sup.01 and Y.sup.02 are, independently of each other, F, Cl or CN, and alternatively one of them may be H, R.sup.01 and R.sup.02 are, independently of each other, H or alkyl with 1 to 12 C-atoms, and L.sup.1 and X.sup.1 have the respective meanings given in claim 2.

5. The mesogenic medium according to claim 2, further comprising one or more compounds selected from formulae I-A, I-E, I-N and I-T ##STR00208## wherein R.sup.0 is alkyl with 1 to 9 C-atoms, which is straight chain or branched, unsubstituted, mono- or poly-substituted by F, Cl or CN, and in which one or more CH.sub.2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NR.sup.01—, —SiR.sup.01R.sup.02—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CY.sup.01═CY.sup.02— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, R.sup.1 is alkyl with 1 to 9 C-atoms, which is straight chain or branched, unsubstituted, mono- or poly-substituted by F, Cl or CN, and in which one or more CH.sub.2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NR.sup.01—, —SiR.sup.01R.sup.02—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CY.sup.01═CY.sup.02— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, Y.sup.01 and Y.sup.02 are, independently of each other, F, Cl or CN, and alternatively one of them may be H, R.sup.01 and R.sup.02 are, independently of each other, H or alkyl with 1 to 12 C-atoms, and L.sup.01 to L.sup.03, L.sup.1, L.sup.11 and L.sup.12 are independently of one another H or F.

6. The mesogenic medium according to claim 2, further comprising one or more compounds of formula II ##STR00209## wherein L.sup.21 to L.sup.23 are, independently of each other, H or F, R.sup.2 is alkyl, which is straight chain or branched, is unsubstituted, mono- or poly-substituted by F, Cl or CN, and in which one or more CH.sub.2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NR.sup.01—, —SiR.sup.01R.sup.02—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CY.sup.01═CY.sup.02— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, Y.sup.01 and Y.sup.02 are, independently of each other, F, Cl or CN, and alternatively one of them may be H, and R.sup.01 and R.sup.02 are, independently of each other, H or alkyl with 1 to 12 C-atoms.

7. The mesogenic according to claim 2, further comprising one or more compounds of formula III ##STR00210## wherein R.sup.3 is alkyl with 1 to 9 C-atoms, which is straight chain or branched, unsubstituted, mono- or poly-substituted by F, Cl or CN, and in which one or more CH.sub.2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NR.sup.01—, —SiR.sup.01R.sup.02—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CY.sup.01═CY.sup.02— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, Y.sup.01 and Y.sup.02 are, independently of each other, F, Cl or CN, and alternatively one of them may be H, and R.sup.01 and R.sup.02 are, independently of each other, H or alkyl with 1 to 12 C-atoms.

8. The mesogenic medium according to claim 2, further comprising one or more compounds selected from formulae IV and V ##STR00211## wherein R.sup.4 and R.sup.5 are, independently of each other, alkyl, which is straight chain or branched, having 1 to 20 C-atoms, is unsubstituted, mono- or poly-substituted by F, Cl or CN, and in which one or more CH.sub.2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, L.sup.5 is H or F, ##STR00212## and n and m are each, independently of one another, 0 or 1.

9. The mesogenic medium according to at least claim 2, further comprising a polymerisable component, which comprises one or more polymerisable compounds.

10. The mesogenic medium according to claim 2, further comprising one or more compounds of formula M1 ##STR00213## wherein the parameters have the following meanings: P.sup.1 and P.sup.2 each, independently of one another, a polymerisable group, Sp.sup.1 and Sp.sup.2 each, independently of one another, a single bond or a spacer group, and, wherein alternatively also one or more of P.sup.1-Sp.sup.1- and P.sup.2-Sp.sup.2- may be R.sup.aa, provided that at least one of P.sup.1-Sp.sup.1- and P.sup.2-Sp.sup.2- present in the compound is not R.sup.aa, R.sup.aa H, F, Cl, CN or linear or branched alkyl having 1 to 25 C-atoms, wherein one or more non-adjacent —CH.sub.2— groups, independently of each another, may be replaced by —C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that neither O- nor S-atoms are directly linked to one another, and wherein also one or more H-atoms may be replaced by F, Cl, CN or P.sup.1-Sp.sup.1-, R.sup.0, R.sup.00 each, at each occurrence independently of one another, H or alkyl having 1 to 12 C-atoms, R.sup.y and R.sup.z each, independently of one another, H, F, CH.sub.3 or CF.sub.3, L at each occurrence independently of one another, F, Cl, CN, SCN, SF.sub.5 or linear or branched, optionally mono- or poly-fluorinated, alkyl, alkoxy, alkenyl, alkinyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C-atoms, and r 0, 1, 2, 3 or 4.

11. The mesogenic medium according to claim 2, further comprising one or more compounds of formula M2 ##STR00214## wherein the parameters have the following meanings: P.sup.1 and P.sup.2 each, independently of one another, a polymerisable group, Sp.sup.1 and Sp.sup.2 each, independently of one another, a single bond or a spacer group, and, wherein alternatively also one or more of P.sup.1-Sp.sup.1- and P.sup.2-Sp.sup.2- may be R.sup.aa, provided that at least one of P.sup.1-Sp.sup.1- and P.sup.2-Sp.sup.2- present in the compound is not R.sup.aa, R.sup.aa H, F, Cl, CN or linear or branched alkyl having 1 to 25 C-atoms, wherein one or more non-adjacent —CH.sub.2— groups, independently of each another, may be replaced by —C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that neither O- nor S-atoms are directly linked to one another, and wherein also one or more H-atoms may be replaced by F, Cl, CN or P.sup.1-Sp.sup.1-, R.sup.0, R.sup.00 each, at each occurrence independently of one another, H or alkyl having 1 to 12 C-atoms, R.sup.y and R.sup.z each, independently of one another, H, F, CH.sub.3 or CF.sub.3, L at each occurrence independently of one another, F, Cl, CN, SCN, SF.sub.5 or linear or branched, optionally mono- or poly-fluorinated, alkyl, alkoxy, alkenyl, alkinyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C-atoms, and r 0, 1, 2, 3 or 4.

12. A method of stabilisation of a mesogenic medium, said method comprising subjecting a medium according to claim 9 to polymerisation of its polymerisable constituents.

13. A mesogenic medium stabilized by polymerisation of the polymerisable constituents of a medium according to claim 9.

14. A light modulation element comprising a medium according to claim 2.

15. An electro-optical display comprising a medium according to claim 2.

16. A method of modulating light comprising applying a voltage to a light modulation element according to claim 14.

17. A compound according to claim 1, wherein R.sup.1 is n-alkyl and X.sup.1 is CF.sub.3.

Description

EXAMPLES

(1) The examples below illustrate the present invention without limiting it in any way.

(2) However, the physical properties show the person skilled in the art what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

(3) Liquid-crystal mixtures having the composition and properties as indicated in the following tables are prepared and investigated.

(4) The so-called “HTP” denotes the helical twisting power of an optically active or chiral substance in an LC medium (in μm.sup.−1). Unless indicated otherwise, the HTP is measured in the commercially available nematic LC host mixture MLD-6260 (Merck KGaA) at a temperature of 20° C.

Synthesis Example 1: 6-(4-{[4-(6-Acryloyloxyhexyl)phenoxy]-difluoromethyl}-3,5-difluorophenyl)hexyl acrylate

1.1: 5-Bromo-2[(4-bromophenoxy)difluoromethyl]-1,3-difluorobenzene

(5) ##STR00161##

(6) 92.0 g (0.200 mol) of 2-(4-bromo-2,6-difluorophenyl)-5,6-dihydro-4H-1,3-dithiyn-1-ylium triflate are initially introduced in 600 ml of dichloromethane (short DCM), and a solution of 52.0 g (0.300 mol) of 4-bromophenol in 200 ml of DCM and 45 ml of triethylamine is added at −70° C. When the addition is complete, the mixture is stirred at −70° C. for a further 1 h, 160 ml (1.00 mol) of triethylamine trishydrofluoride are added, and a solution of 51.0 ml (0.996 mol) of bromine in 200 ml of DCM is subsequently added in drops. After 1 h, the cooling is removed, and, after warming to −10° C., the batch is added to a solution of 310 ml of 32 percent sodium hydroxide solution in 2 l of ice-water. The org. phase is separated off and washed with water. The aqueous phase is extracted with DCM, and the combined org. phases are dried over sodium sulphate. The solvent is removed in vacuo, and the residue is filtered through silica gel with heptane, giving 5-bromo-2-[(4-bromophenoxy)-difluoromethyl]-1,3-difluorobenzene as a yellow oil.

(7) .sup.19F-NMR (CDCl.sub.3, 235 MHz)

(8) δ=−63.1 ppm (t, J=26.7 Hz, 2F, —CF.sub.2O—), −112 (dt, J=9.7 Hz, J=26.7 Hz, 2 F, Ar—F).

1.2: 6-(4-{Difluoro[4-(6-hydroxyhex-1-ynyl)phenoxy]methyl}-3,5-difluorophenyl)hex-5-yn-1-ol

(9) ##STR00162##

(10) 10.7 g (25.8 mmol) of 5-bromo-2-[(4-bromophenoxy)difluoromethyl]-1,3-difluorobenzene and 8.00 g (81.5 mmol) of hex-5-yn-1-ol are initially introduced in 11.3 ml of triethylamine and 500 ml of toluene, 1.50 g (2 mmol) of bis(triphenylphosphine)palladium(II) chloride and 0.700 g (3.68 mmol) of copper(I) iodide are added, and the mixture is heated under reflux overnight. The batch is subsequently added to water, neutralised using 2 N hydrochloric acid and extracted three times with toluene. The combined org. phases are dried over sodium sulphate, the solvent is removed in vacuo, and the residue is chromatographed on silica gel firstly with toluene and then with toluene/ethyl acetate (4:1), giving 6-(4-{difluoro[4-(6-hydroxyhex-1-ynyl)phenoxy]methyl}-3,5-difluorophenyl)hex-5-yn-1-ol as a colourless solid.

1.3: 6-(4-{Difluoro[4-(6-hydroxyhexyl)phenoxy]methyl}-3,5-difluorophenyl)hexan-1-ol

(11) ##STR00163##

(12) 6-(4-{Difluoro[4-(6-hydroxyhex-1-ynyl)phenoxy]methyl}-3,5-difluorophenyl)-hex-5-yn-1-ol is hydrogenated to completion on palladium/active carbon catalyst in tetrahydrofurane (short THF). The catalyst is filtered off, the solvent is removed in vacuo, and the crude product is chromatographed on silica gel with toluene/ethyl acetate (1:2), giving 6-(4-{difluoro[4-(6-hydroxyhexyl)phenoxy]methyl}-3,5-difluorophenyl)hexan-1-ol as a colourless solid.

(13) .sup.19F-NMR (CDCl.sub.3, 235 MHz)

(14) δ=−60.8 ppm (t, J=26.3 Hz, 2 F, —CF.sub.2O—), −112 (dt, J=10.0 Hz, J=26.3 Hz, 2 F, Ar—F).

1.4: 6-(4-{[4-(6-Acryloyloxyhexyl)phenoxy]difluoromethyl}-3,5-difluorophenyl)hexyl acrylate

(15) ##STR00164##

(16) 17.0 g (37.2 mmol) of 6-(4-{difluoro[4-(6-hydroxyhexyl)phenoxy]methyl}-3,5-difluorophenyl)hexan-1-01, 8.05 g (112 mmol) of acrylic acid and 0.5 g of DMAP are initially introduced in 300 ml of DCM, and a solution of 17.3 g (112 mmol) of EDC in 75 ml of DCM is added in drops with ice cooling. After 1 h, the cooling is removed, and the batch is left to stir overnight at room temp. The vast majority of the solvent is removed in vacuo, and the residue is chromatographed on silica gel with DCM, giving 6-(4-{[4-(6-acryloyloxyhexyl)phenoxy]difluoromethyl}-3,5-difluorophenyl)hexyl acrylate as a colourless oil.

(17) Phase behaviour: T.sub.g −71° C. K 13 I.

(18) .sup.1H-NMR (CDCl.sub.3, 250 MHz)

(19) δ=1.25-1.48 ppm (m, 8H, CH.sub.2), 1.50-1.74 ppm (m, 8H, CH.sub.2), 2.60 (m, 4H, 2-Ar—CH.sub.2—), 4.13 (t, J=6.7 Hz, 2H, —CH.sub.2O—), 4.15 (t, J=6.7 Hz, 2H, —CH.sub.2O—), 5.81 (dt, J=10.4 Hz, J=1.8 Hz, 2H, 2 CHH═CH—COO—), 6.11 (m.sub.c, 2H, 2 CH.sub.2═CH—COO—), 6.39 (2 CHH═CH—COO—), 6.78 (d, J=10.0 Hz, 2H, Ar—H), 7.15 (m.sub.c, 4 H, Ar—H).

(20) .sup.19F-NMR (CDCl.sub.3, 235 MHz)

(21) δ=−60.9 ppm (t, J=26.4 Hz, 2 F, —CF.sub.2O—), −112.0 (dt, J=26.4, J=10.0 Hz, 2 F, Ar—F).

(22) The following reactive compounds are obtained analogously.

(23) ##STR00165##

(24) Phase behaviour: to be determined.

(25) ##STR00166##

(26) Phase behaviour: T.sub.g −66° C. I.

(27) ##STR00167##

(28) Phase behaviour: T.sub.g −69° C. I.

(29) ##STR00168##

(30) Phase behaviour: to be determined.

(31) ##STR00169##

(32) Phase behaviour: to be determined.

(33) ##STR00170##

(34) Phase behaviour: to be determined.

(35) ##STR00171##

(36) Phase behaviour: to be determined.

(37) ##STR00172##

(38) Phase behaviour: C 128° C. I.

(39) ##STR00173##

(40) Phase behaviour: T.sub.g −59° C. N −28.5° C. I.

Synthesis Example 2

(41) ##STR00174##
Step 2.1:

(42) ##STR00175##

(43) 150 g (0.67 mole) 4-bromo-2-fluorobenzoic acid are dissolved in 750 ml dry methanol. 1.865 ml (0.03 mole) sulphuric acid (98.0%) are added in drops. The mixture is heated under reflux for 16 h, left to cool to ambient temperature and the solvent evaporated to yield a slightly yellow residue. The crude product is re-crystallized twice from ethanol.

(44) Step 2.2:

(45) ##STR00176##

(46) 34 g (14 mmole) of the product of the previous step, step 2.1, are dissolved in 365 ml 1,4dioxane. Then 3.13 mg of PdCl.sub.2-dppf, 42.522 g bis-(pinacolato)-diborane and 42.023 g potassium acetate are added. The resultant mixture is heated under reflux for 16 h. Then the resultant mixture is allowed to cool to ambient temperature. The product is purified as usual to yield 30 g of slightly yellow crystals.

(47) Step 2.3:

(48) ##STR00177##

(49) 19.692 g of sodium bicarbonate are dissolved in 174 ml water. Subsequently 20.0 g (11 mmole) 4-n-butyl-2-chloro-pyrimidine and 33.621 g (11 mmole) of the product from the previous step, step 2.2, dissolved in 450 ml THF are added. The resultant mixture is stirred and thoroughly degassed. Then 150 mg bis(tri-tert-butylphosphine)palladium(0) in 50 ml THF are added. The mixture is heated under reflux for 16 h. After the resultant mixture has been allowed to cool to ambient temperature water and methyl-tert-butyl (short MtB) ether are added and the phases are separated. The organic phase is dried and the solvent evaporated. The crude product is obtained as a beige coloured solid.

(50) Step 2.4:

(51) ##STR00178##

(52) 16.700 g of the product from the previous step, step 1.3, are dissolved in 500 g ethanol. Then 41.278 ml 2 N aqueous potassium hydroxide (NaOH) are added. The resultant mixture is stirred for 1 h at a temperature of 45° C. After stirring for additional 2 h the reaction is completed. The reaction mixture is allowed to cool to ambient temperature. Then ice water is added leading to an turbid mixture and the pH value is set to 3 to 4 by adding diluted hydrochloric acid and then MtB ether is added. The phases are separated. The organic phase is dried with potassium sulphate and the solvent evaporated. The product is obtained as white crystals resembling cotton wool.

(53) Step 2.5:

(54) ##STR00179##

(55) 169.64 g of 1-bromo-3,5-difluoro-4-trifluoromethylbenzene (C.sub.7H.sub.2BrF.sub.5, from company Fluorochem) are dissolved in 70 ml THF and cooled to a temperature of approximately −5° C. under inert gas (N.sub.2). At this temperature 357.50 ml of a solution of iso-propylmagnesium chloride (2.0 mole/I) in THF are slowly added. Then the mixture is stirred at this temperature for 1 h. Then 90.59 ml trimethyl borate in 100 ml THF are added in drops. During the addition the temperature is always kept between 0 and −5° C. Then the mixture is stirred for 30 min. At −5° C. Subsequently the mixture is poured into 410 ml ice cooled hydrochloric acid (10%). The product is extracted with 300 ml heptanes, washed with water and the solvent evaporated. The product obtained is an almost colourless solid.

(56) Step 2.6:

(57) ##STR00180##

(58) 134.00 g of the boronic acid, the product from the previous step, step 2.5, are dissolved in 425 ml THF. Then 73.81 ml acetic acid (100%) are added and the mixture is heated to a temperature of approximately 55° C. At this temperature 74.90 ml aqueous hydrogen peroxide solution (30.0%) is added in drops. The temperature is always kept between 55 and 60° C. during this process. Then the mixture is stirred for 90 min. At a temperature between 55 and 60° C. and subsequently cooled to 15° C. Then 300 ml ice cooled water is added and the resultant mixture acidified with 45 ml hydrochloric acid (25%). The resultant pH is approximately 2. Then further 500 ml water are added. The clear organic phase is separated. The aqueous phase is extracted with 200 ml DCM. The combined organic phases are treated twice with a solution of ammonium iron(II) sulphate, until the aqueous phase does not turn brown any more, then washed once again with water, dried and the solvent evaporated. The raw product is purified by solution in 300 ml MtB ether and addition of 300 ml water. Then solid sodium bicarbonate is added until the aqueous phase is neutral or slightly alkaline. It has a pH of approximately 7 to 8. The organic phase is separated, dried and the solvent evaporated. The product is obtained as a slightly yellow oil.

(59) Step 2.7:

(60) ##STR00181##
Step 2.8:

(61) ##STR00182##

(62) 16.394 g of di-iso-propylammonium 3-trifluoromethyl-4,6-difluorophenolate (C.sub.7H.sub.2F.sub.5O*C.sub.6H.sub.16N) the product of the previous step, step 2.7 and 0.608 g 4-(dimethylamino)-pyridine are dissolved in 70 ml dichloromethane. The mixture is cooled to a temperature of 10° C. Then, under further gentle cooling, 9.805 ml 1-(3-dimethylaminopropyle)-3-ethylcarbodiimide dissolved in 20 ml DCM are added in drops. Subsequently 13.700 g of the product from step 2.4 dissolved in a mixture of 100 ml DCM and 50 ml THF are added in drops over a time span of about 10 minutes while the temperature of the mixture is kept at about 10° C. Then the mixture is stirred for 2 h at ambient temperature, the solvent is evaporated and the product obtained as a slightly coloured solid after usual purification.

(63) ##STR00183##
Phase sequence: K 81° C. SmA 138° C. I. Δ∈=55.7 and Δn=0.166.

(64) The following compounds are prepared analogously.

(65) ##STR00184##
Phase sequence: K 73° C. SmA 141° C. I. Δ∈=52.4 and Δn=0.174.

(66) ##STR00185##
Phase sequence: K 56° C. SmC (50° C.) SmA 151° C. I. Δ∈=43.8 and Δn=0.180.

(67) ##STR00186##
Phase sequence: K 95° C. SmA 115° C. N 153.8° C. I. Δ∈=76.9 and Δn=0.175.

(68) ##STR00187##
Phase sequence: t.b.d., Δ∈=t.b.d. and Δn=t.b.d.

(69) ##STR00188##
Phase sequence: t.b.d., Δ∈=t.b.d. and Δn=t.b.d.

Synthesis Example 3

(70) ##STR00189##
Step 3.1:

(71) ##STR00190##

(72) 84.92 g 1-Bromo-3,5-difluor-benzene, 9.69 g PdCl.sub.2-dppf, 129.55 g potassium acetate and 167.61 g bis-(pinacolato)-diborane are dissolved in 1,000 ml 1,4-dioxane and heated for 16 h under reflux under inert gas (N.sub.2). The crude product is obtained and purified as usual.

(73) Step 3.2:

(74) ##STR00191##

(75) 21.84 g pure solid potassium hydrogen carbonate are dissolved in 200 ml water. Then 22.18 g 5-butyl-2-chloro-pyrimidine and 37.95 g of the product of the previous step, step 3.1, dissolved in 340 ml THF are added. The combined mixture is stirred and thoroughly degassed. Then 166 mg of bis-(tri-tert-butylphosphine)palladium (0) dissolved in 60 ml THF are added. The resultant mixture is stirred and heated under reflux for 16 h. The product is purified as usual and obtained as colourless crystals.

(76) Step 3.3:

(77) ##STR00192##

(78) 30.80 g of the product of the previous step, step 3.2, are dissolved in 500 ml THF and cooled under inert gas (N.sub.2) to a temperature of −70° C. At this temperature 118.38 ml solution of LDA in THF are added in drops. Then the mixture is stirred for 1 h. Subsequently 8.14 g solid carbon dioxide are allowed to evaporate and the gas is led into the reaction vessel slowly. During this process the temperature is always kept below −55° C. After the reaction is completed the cooling is stopped and the reaction mixture allowed to heat up to a temperature of −10° C. Then it is poured into 500 ml of water and acidified with hydrochloric acid. The organic phase is separated, dried and the solvent evaporated. After usual purification the product is obtained as colourless crystals.

(79) Step 3.4:

(80) ##STR00193##

(81) 169.64 g di-iso-propylammonium 3-trifluoromethyl-4,6-difluorophenolate (C.sub.7H.sub.2BrF.sub.5), prepared from the phenol and the base) are dissolved in 70 ml THF and cooled to a temperature of approximately −5° C. under inert gas (N.sub.2). At this temperature 357.50 ml of a solution of isopropylmagnesium chloride (2.0 mole/l) in THF are added in drops. Then the mixture is stirred at this temperature for 1 h. Subsequently 90.59 ml trimethyl borate in 100 ml THF are added in drops. During the addition the temperature is always kept between 0 and −5° C. Then the mixture is stirred for 30 min. at −5° C. After that the mixture is poured into 410 ml ice cooled hydrochloric acid (10%). The product is extracted with 300 ml heptane, washed with water and the solvent evaporated. The product obtained is an almost colourless solid.

(82) Step 3.5:

(83) ##STR00194##

(84) 134.00 g of the boronic acid, the product from the previous step, step 3.4, are dissolved in 425 ml THF. 73.81 ml acetic acid (100%) are added and the mixture is heated to a temperature of approximately 55° C. At this temperature 74.90 ml aqueous hydrogen peroxide solution n(30.0%) is added in drops. The temperature is always kept between 55 and 60° C. during this process. Then the mixture is stirred for 90 min. at a temperature between 55 and 60° C. and subsequently cooled to 15° C. Then 300 ml ice cooled water is added and the resultant mixture acidified with 45 ml hydrochloric acid (25%). The resultant pH is approximately 2. Then further 500 ml water are added. The clear organic phase is separated. The aqueous phase is extracted with 200 ml DCM. The combined organic phases are treated twice with a solution of ammonium iron(II) sulphate, until the aqueous phase does not turn brown any more, then washed once again with water, dried and the solvent evaporated. The raw product is purified by solution in 300 ml MtB ether and addition of 300 ml water. Then solid sodium bicarbonate is added until the aqueous phase is neutral or slightly alkaline (pH of approximately 7 to 8). The organic phase is separated, dried and the solvent evaporated. The product is obtained as a slightly yellow oil.

(85) Step 3.6:

(86) ##STR00195##

(87) 13.99 g of the product of step 3.3 are dissolved in 180 ml DCM and stirred under inert gas (N.sub.2). The temperature drops to approximately 18° C. Subsequently 0.567 g 4-(dimethyl-amino)-pyridine (short DMAP) and 3,5-difluoro-4-trifluoromethyl-phenole (the product from the previous step, step 3.5) dissolved in 20 ml DCM are added. A clear solution with a temperature of 19° C. is obtained. Then 10.28 g N,N′-dicyclohexylcarbodiimide (short DCC) dissolved in 30 ml DCM are added in drops over a time span of 10 min. The temperature rises to approximately 27° C. and a precipitate of dicyclohexylurea forms. The resultant mixture is stirred for 16 h. Then 1.27 g oxalic acid dihydrate are added and the mixture is stirred for another 2 h. The crude product is obtained and purified as usual. After repeated re-crystallisation from 2-propanole the product is obtained in the form of colourless crystals.

(88) ##STR00196##
Phase sequence: K 57° C. SmA 74° C. I. Δ∈=54.8 and Δn=0.149.

(89) The following compounds are prepared analogously.

(90) ##STR00197##
Phase sequence: K 103° C. I. Δ∈=60.7 and Δn=0.153.

(91) ##STR00198##
Phase sequence: K 67° C. SmA 86° C. I. Δ∈=49.8 and Δn=0.149.

(92) ##STR00199##
Phase sequence: K124° C. SmA (90° C.) 126.4° C. I. Δ∈ and Δn=t.b.d.

(93) ##STR00200##
Phase sequence: K 93° C. SmA 57° C. 112.7° C. I. Δ∈=83.1 and Δn=0.194.

(94) ##STR00201##
Phase sequence: K 68° C. SmA (47° C.) N 115.1° C. I. Δ∈=78.9 and Δn=0.192.

COMPOSITION AND USE EXAMPLES

Example 1

(95) The following liquid crystalline mixture M-1 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(96) TABLE-US-00007 Composition and properties liquid crystal mixture M-1 Composition Compound Conc./ No. Abbreviation mass-% 1 MGZU-5-T 10.0 2 PZG-2-N 12.0 3 GUQU-2-N 13.0 4 GUQU-3-N 12.0 5 GUUQU-3-N 10.0 6 GUUQU-4-N 10.0 7 GUQGU-2-T 10.0 8 DUUQU-3-F 9.0 9 DUUQU-4-F 9.0 10  DUUQU-5-F 9.0 Σ 100.0 Physical Properties T (N, I) = 67° C. n.sub.o (20° C., 589 nm) = t.b.d. Δn (20° C., 589 nm) = t.b.d. ε.sub.⊥ (20° C., 1 kHz) = t.b.d. Δε (20° C., 1 kHz) = t.b.d. γ.sub.1 (20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

(97) 4.2% of the chiral agent R-5011 are solved in the achiral liquid crystal mixture and the electro-optical response of resultant mixtures in IPS-type cells is investigated. The mixture is filled into an electro optical test cells with inter-digital electrodes on one substrate side. The electrode width is 10 μm, the distance between adjacent electrodes is 10 μm and the cell gap is also 10 μm. These test cells are evaluated electro-optically between crossed polarisers.

(98) Appropriate Concentrations

(99) a) of the chiral dopant R-5011 (Merck KGaA, Germany),

(100) b) of the reactive mesogen of the formula RM-C

(101) ##STR00202##
and
c) alternatively of one of the two reactive mesogenic compounds of the formulae RM-1

(102) ##STR00203##
and RM-2

(103) ##STR00204##
respectively, are added to the mixture of interest, here mixture M-1. The resultant mixture is introduced into test cells and heated to an appropriate temperature, at which the mixture is in the blue phase. Then it is exposed to UV.

(104) The mixtures are characterised as described below before the polymerisation. The reactive components are then polymerised in the blue phase by irradiation once (180 s), and the resultant media are recharacterised.

(105) Detailed Description of the Polymerisation

(106) Before the polymerisation of a sample, the phase properties of the medium are established in a test cell having a thickness of about 10 microns and an area of 2×2.5 cm.sup.2. The filling is carried out by capillary action at a temperature of 75° C. The measurement is carried out under a polarising microscope with heating stage with a temperature change of 1° C./min.

(107) The polymerisation of the media is carried out by irradiation with a UV lamp (Dymax, Bluewave 200, 365 nm interference filter) having an effective power of about 3.0 mW/cm.sup.2 for 180 seconds. The polymerisation is carried out directly in the electro-optical test cell.

(108) The polymerisation is carried out initially at a temperature at which the medium is in the blue phase I (BP-I). The polymerisation is carried out in a plurality of part-steps, which gradually result in complete polymerisation. The temperature range of the blue phase generally changes during the polymerisation. The temperature is therefore adapted between each part-step so that the medium is still in the blue phase. In practice, this can be carried out by observing the sample under the polarising microscope after each irradiation operation of about 5 s or longer. If the sample becomes darker, this indicates a transition into the isotropic phase. The temperature for the next part-step is reduced correspondingly.

(109) The entire irradiation time which results in maximum stabilisation is typically 180 s at the irradiation power indicated. Further polymerisations can be carried out in accordance with an optimised irradiation/temperature programme.

(110) Alternatively, the polymerisation can also be carried out in a single irradiation step, in particular if a broad blue phase is already present before the polymerisation.

(111) Electro-Optical Characterisation

(112) After the above-described polymerisation and stabilisation of the blue phase, the phase width of the blue phase is determined. The electro-optical characterisation is carried out subsequently at various temperatures within and if desired also outside this range.

(113) The test cells used are fitted on one side with interdigital electrodes on the cell surface. The cell gap, the electrode separation and the electrode width are typically each 10 microns. This uniform dimension is referred to below as the gap width. The area covered by electrodes is about 0.4 cm.sup.2. The test cells do not have an alignment layer.

(114) For the electro-optical characterisation, the cell is located between crossed polarising filters, where the longitudinal direction of the electrodes adopts an angle of 45° to the axes of the polarising filter. The measurement is carried out using a DMS301 (Autronic-Melchers, Germany) at a right angle to the cell plane, or by means of a highly sensitive camera on the polarising microscope. In the voltage-free state, the arrangement described gives an essentially dark image (definition 0% transmission).

(115) Firstly, the characteristic operating voltages and then the response times are measured on the test cell. The operating voltage is applied to the cell electrodes in the form of rectangular voltage having an alternating sign (frequency 100 Hz) and variable amplitude, as described below.

(116) The transmission is measured while the operating voltage is increased. The attainment of the maximum value of the transmission defines the characteristic quantity of the operating voltage V.sub.100. Equally, the characteristic voltage V.sub.10 is determined at 10% of the maximum transmission. These values are measured at various temperatures in the range of the blue phase.

(117) Relatively high characteristic operating voltages V.sub.100 are observed at the upper and lower end of the temperature range of the blue phase. In the region of the minimum operating voltage, V.sub.100 generally only increases slightly with increasing temperature. This temperature range, limited by T.sub.1 and T.sub.2, is referred to as the usable, flat temperature range (FR). The width of this “flat range” (FR) is (T.sub.2−T.sub.1) and is known as the width of the flat range (WFR). The precise values of T.sub.1 and T.sub.2 are determined by the intersections of tangents on the flat curve section FR and the adjacent steep curve sections in the V.sub.100/temperature diagram.

(118) In the second part of the measurement, the response times during switching on and off (τ.sub.on, τ.sub.off) are determined. The response time τ.sub.on is defined by the time to achievement of 90% intensity after application of a voltage at the level of V.sub.100 at the selected temperature. The response time τ.sub.off is defined by the time until the decrease by 90% starting from maximum intensity at V.sub.100 after reduction of the voltage to 0 V. The response time is also determined at various temperatures in the range of the blue phase.

(119) As further characterisation, the transmission at continuously increasing and falling operating voltage between 0 V and V.sub.100 is measured at a temperature within the FR. The difference between the two curves is known as hysteresis. The difference in the transmissions at 0.5.Math.V.sub.100 and the difference in the voltages at 50% transmission are, for example, characteristic hysteresis values and are known as ΔT.sub.50 and ΔV.sub.50 respectively.

(120) As a further characteristic quantity, the ratio of the transmission in the voltage-free state before and after passing through a switching cycle can be measured. This transmission ratio is referred to as the “memory effect”. The value of the memory effect is 1.0 in the ideal state. Values above 1 mean that a certain memory effect is present in the form of excessively high residual transmission after the cell has been switched on and off. This value is also determined in the working range of the blue phase (FR).

(121) Typical concentrations of the polymer precursors are as follows.

(122) TABLE-US-00008 Sample 1.1 1.2 Constituent Concentration/% M-1 84.6 83.6 R-5011 4.2 4.2 RM-C 7.5 7.5 RM-1 0.0 0.0 RM-2 3.5 4.5 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

(123) The results are summarised in the following table.

(124) TABLE-US-00009 Mixture M-1-1 M-1-2 Host M-1 M-1 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 32.8 30.2 Polymerisation temperature/° C. 33.3 30.7 V.sub.10 (25° C.)/V 3.7 3.8 V.sub.50 (25° C.)/V 6.2 8.2 V.sub.90 (25° C.)/V 8.7 11.4 V.sub.100 (25° C.)/V 11 15 ΔV.sub.50 (25° C.)/V 1.01 5.83 τ.sub.on (25° C.)/ms 6.62 1.73 τ.sub.off (25° C.)/ms 1.11 2.66

(125) Remark: t.b.d.: to be determined

(126) TABLE-US-00010 Sample 1.3 1.4 Constituent Concentration/% M-1 83.6 83.6 R-5011 4.2 4.2 RM-C 8.0 8.5 RM-1 0.0 0.0 RM-2 4.0 3.5 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

(127) TABLE-US-00011 Mixture M-1-3 M-1-4 Host M-1 M-1 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 31.0 31.5 Polymerisation temperature/° C. 31.5 32.0 V.sub.10 (25° C.)/V 4.3 2.7 V.sub.50 (25° C.)/V 7.9 5.1 V.sub.90 (25° C.)/V 11.1 7.6 V.sub.100 (25° C.)/V 14 10 ΔV.sub.50 (25° C.)/V 3.11 1.85 τ.sub.on (25° C.)/ms 4.38 3.29 τ.sub.off (25° C.)/ms 6.44 1.65

(128) Remark: t.b.d.: to be determined

(129) The polymerisable mixture is polymerised in a single irradiation step at a temperature of about 30-50° C. at the lower end of the temperature range of the blue phase. The polymer-stabilised liquid-crystalline media exhibit a blue phase over a broad temperature range.

(130) The polymer-stabilised media M-1-1 to M-1-4 prepared using the monomer (RM-2) according to the invention, exhibit a small hysteresis (ΔV.sub.50) and good contrast for switching on and on switching off compared with conventional media from the prior art. In particular, the contrast on switching on and the contrast on switching off are close together in the media M-1-1, M-1-2, M-1-3 and M-1-4 according to the invention, which indicates a very good stabilisation of the blue phase.

(131) It can be seen from this that the monomers according to the invention are particularly suitable for the stabilisation of blue phases, in particular in the case of media having a high concentration of chiral dopant.

Comparative Examples 1-1 and 1-2

(132) The following liquid crystalline mixture (C-1) is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(133) TABLE-US-00012 Composition and properties liquid crystal mixture C-1 Composition Compound Conc./ No. Abbreviation mass-% 1 AUUQU-2-F 10.0 2 AUUQU-3-F 11.0 3 AUUQU-4-F 7.0 4 AUUQU-5-F 6.0 5 AUUQU-7-F 7.0 6 AUUQU-3-T 10.0 7 AUUQU-3-OT 11.0 8 AGUQU-3-F 4.0 9 AUUQU-3-N 5.0 10 PUZU-2-F 7.0 11 PUZU-3-F 11.0 12 PUZU-5-F 11.0 Σ 100.0 Physical Properties T (N, I) = 71° C. n.sub.o (20° C., 589 nm) = 1.4812 Δn (20° C., 589 nm) = 0.1543 ε.sub.⊥ (20° C., 1 kHz) = 14.8 Δε (20° C., 1 kHz) = 212 γ.sub.1 (30° C.) = 763 mPa .Math. s

(134) This mixture is treated and investigated as described in detail under example 1 above.

(135) The results are compiled in the following table.

(136) TABLE-US-00013 Mixture C-1-1 C-1-2 Host C-1 Reactive mesogen RM-1 RM-2 Measurement values (20° C.) Transition point before the polymerisation t.b.d. t.b.d. Polymerisation temperature/° C. t.b.d. t.b.d. V.sub.10 (20° C.)/V 29.8 20.8 V.sub.50 (20° C.)/V t.b.d. t.b.d. V.sub.90 (20° C.)/V 58.6 42.0 V.sub.100 (20° C.)/V 67.0 47.9 ΔV.sub.50 (20° C.)/V 4.73 1.90 Memory effect 1.04 0.99 Remarks: t.b.d.: to be determined

Comparative Example 2

(137) The following liquid crystalline mixture (C-2) is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(138) TABLE-US-00014 Composition and properties liquid crystal mixture C-2 Composition Compound Conc./ No. Abbreviation mass-% 1 GUQU-3-F 5.0 2 GUQU-4-F 6.0 3 GUQU-5-F 6.0 4 PUQGU-3-T 8.0 5 PUQGU-5-T 8.0 6 GUQGU-2-T 12.0 7 GUQGU-3-T 12.0 8 GUQGU-4-T 14.0 9 GUQGU-5-T 14.0 10  GUQU-3-N 5.0 11  GUUQU-3-N 10.0 Σ 100.0 Physical Properties T (N, I) = 65° C. n.sub.o (20° C., 589 nm) = 1.4831 Δn (20° C., 589 nm) = 0.1859 ε.sub.⊥ (20° C., 1 kHz) = 12.9 Δε (20° C., 1 kHz) = 277.8

(139) The results are compiled in the following table.

(140) TABLE-US-00015 Mixture CM-2-1 CM-2-2 Host C-2 Reactive mesogen RM-1 RM-2 Measurement values (20° C.) Transition point before the polymerisation t.b.d. t.b.d. Polymerisation temperature/° C. t.b.d. t.b.d. V.sub.10 (20° C.)/V t.b.d. 19.5 V.sub.50 (20° C.)/V t.b.d. t.b.d. V.sub.90 (20° C.)/V t.b.d. 38.2 V.sub.100 (20° C.)/V t.b.d. 43.0 ΔV.sub.50 (20° C.)/V t.b.d. 2.16 Memory effect t.b.d. 1.03 V.sub.100 (30° C.)/V t.b.d. 52.0 Memory effect t.b.d. 1.10 Remarks: t.b.d.: to be determined

Example 2

(141) The following liquid crystalline mixture M-2 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(142) TABLE-US-00016 Composition and properties liquid crystal mixture M-2 Composition Compound Conc./ No. Abbreviation mass-% 1 MGZU-5-T 12.0 2 PZG-2-N 8.0 3 GUQU-2-N 12.0 4 GUQU-3-N 12.0 5 GUUQU-3-N 10.0 6 GUUQU-4-N 10.0 7 GUQGU-2-T 9.0 8 GUQGU-3-T 9.0 9 DUUQU-4-F 9.0 10  DUUQU-5-F 9.0 Σ 100.0 Physical Properties T (N, I) = t.b.d. ° C. n.sub.o (20° C., 589 nm) = t.b.d. Δn (20° C., 589 nm) = t.b.d. ε.sub.⊥ (20° C., 1 kHz) = t.b.d. Δε (20° C., 1 kHz) = t.b.d. γ.sub.1 (20° C.) = t.b.d. mPa .Math. s Remarks: t.b.d.: to be determined

(143) Typical concentrations of the polymer precursors are as follows.

(144) TABLE-US-00017 Sample 2.1 2.2 Constituent Concentration/% M-2 84.6 83.6 R-5011 4.2 4.2 RM-C 7.5 7.5 RM-1 0.0 0.0 RM-2 3.5 4.5 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

(145) The results are summarised in the following table.

(146) TABLE-US-00018 Mixture 2.1 2.2 Host M-2 M-2 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 34.5 t.b.d. Polymerisation temperature/° C. 35.0 t.b.d. V.sub.10 (25° C.)/V 3.6 t.b.d. V.sub.50 (25° C.)/V 6.5 t.b.d. V.sub.90 (25° C.)/V 9.5 t.b.d. V.sub.100 (25° C.)/V 12.4 t.b.d. ΔV.sub.50 (25° C.)/V 1.64 t.b.d. τ.sub.on (25° C.)/ms 6.6 t.b.d. τ.sub.off (25° C.)/ms 12.9 t.b.d. Remark: t.b.d.: to be determined

Example 3

(147) The following liquid crystalline mixture M-3 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(148) TABLE-US-00019 Composition and properties liquid crystal mixture M-3 Composition Compound Conc./ No. Abbreviation mass-% 1 MUZU-4-T 8.0 2 MUZU-5-T 8.0 3 PZG-2-N 9.0 4 PZG-3-N 9.0 5 UM-4-N 7.0 6 GUUQU-4-N 8.0 7 GUUQU-5-N 8.0 8 GUQGU-2-T 10.0 9 GUQGU-3-T 10.0 10  DUUQU-3-F 3.0 11  DUUQU-4-F 6.0 12  DUUQU-5-F 6.0 13  DPGU-4-F 8.0 Σ 100.0 Physical Properties T (N, I) = 62.5° C. n.sub.o (20° C., 589 nm) = t.b.d. Δn (20° C., 589 nm) = t.b.d. ε.sub.⊥ (20° C., 1 kHz) = t.b.d. Δε (20° C., 1 kHz) = t.b.d. γ.sub.1 (20° C.) = t.b.d. mPa .Math. s Remarks: t.b.d.: to be determined

(149) Typical concentrations of the polymer precursors are as follows.

(150) TABLE-US-00020 Sample 3.1 3.2 Constituent Concentration/% M-3 82.1 83.6 R-5011 4.7 4.2 RM-C 8.75 7.5 RM-1 0.0 0.0 RM-2 4.25 4.5 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

(151) The results are summarised in the following table.

(152) TABLE-US-00021 Mixture 3.1 3.2 Host M-3 M-3 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 23.2 t.b.d. Polymerisation temperature/° C. 23.7 t.b.d. V.sub.10 (20° C.)/V t.b.d. t.b.d. V.sub.50 (20° C.)/V t.b.d. t.b.d. V.sub.90 (20° C.)/V t.b.d. t.b.d. V.sub.100 (20° C.)/V 54 t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. τ.sub.on (20° C.)/ms 1.49 t.b.d. τ.sub.off (20° C.)/ms 1.33 t.b.d. Memory 1.01 t.b.d. Remarks: t.b.d.: to be determined

Example 4

(153) The following liquid crystalline mixture M-4 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(154) TABLE-US-00022 Composition and properties liquid crystal mixture M-4 Composition Compound Conc./ No. Abbreviation mass-% 1 MGZU-4-T 7.0 2 MGZU-5-T 7.0 3 PZG-2-N 10.0 4 PZG-3-N 10.0 5 UM-4-N 10.0 6 GUUQU-§-N 4.0 7 GUUQU-4-N 4.0 8 GUUQU-5-N 4.0 9 GUQGU-2-T 10.0 10  GUQGU-3-T 10.0 11  DUUQU-3-F 6.0 12  DUUQU-4-F 6.0 13  DUUQU-5-F 6.0 14  DPGU-4-F 6.0 Σ 100.0 Physical Properties T (N, I) = t.b.d. ° C. n.sub.o (20° C.,589 nm) = t.b.d. Δn (20° C., 589 nm) = t.b.d. ε.sub.⊥ (20° C., 1 kHz) = t.b.d. Δε (20° C., 1 kHz) = t.b.d. γ.sub.1 (20° C.) = t.b.d. mPa .Math. s Remarks: t.b.d.: to be determined

(155) Typical concentrations of the polymer precursors are as follows.

(156) TABLE-US-00023 Sample 4.1 4.2 Constituent Concentration/% M-4 82.1 83.6 R-5011 4.7 4.2 RM-C 8.75 7.5 RM-1 0.0 0.0 RM-2 4.25 4.5 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

(157) The results are summarised in the following table.

(158) TABLE-US-00024 Mixture 4.1 4.2 Host M-4 M-4 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 20.7 t.b.d. Polymerisation temperature/° C. 21.2 t.b.d. V.sub.10 (20° C.)/V t.b.d. t.b.d. V.sub.50 (20° C.)/V t.b.d. t.b.d. V.sub.90 (20° C.)/V t.b.d. t.b.d. V.sub.100 (20° C.)/V 53 t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. τ.sub.on (20° C.)/ms 1.32 t.b.d. τ.sub.off (20° C.)/ms 1.24 t.b.d. Memory 1.02 t.b.d. Remarks: t.b.d.: to be determined

Example 5

(159) The following liquid crystalline mixture M-5 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(160) TABLE-US-00025 Composition and properties liquid crystal mixture M-5 Composition Compound Conc./ No. Abbreviation mass-% 1 MGZU-4-T 6.0 2 MGZU-5-T 6.0 3 MUZU-4-T 6.0 4 MUZU-5-T 6.0 5 PZG-2-N 10.0 6 PZG-3-N 10.0 7 PZG-4-N 12.0 8 GUUQU-3-N 6.0 9 GUUQU-4-N 8.0 10  GUUQU-5-N 8.0 11  PGUQU-3-F 6.0 12  PGUQU-4-F 8.0 13  PGUQU-5-F 8.0 Σ 100.0 Physical Properties T (N, I) = 66.5° C. n.sub.o (20° C., 589 nm) = t.b.d. Δn (20° C., 589 nm) = t.b.d. Δ.sub.⊥ (20° C., 1 kHz) = t.b.d. Δε (20° C., 1 kHz) = t.b.d. γ.sub.1 (20° C.) = t.b.d. mPa .Math. s Remarks: t.b.d.: to be determined

(161) Typical concentrations of the polymer precursors are as follows.

(162) TABLE-US-00026 Sample 5.1 5.2 Constituent Concentration/% M-5 82.1 83.6 R-5011 4.7 4.2 RM-C 8.75 7.5 RM-1 0.0 0.0 RM-2 4.25 4.5 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

(163) The results are summarised in the following table.

(164) TABLE-US-00027 Mixture 5.1 5.2 Host M-5 M-5 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 28.9 t.b.d. Polymerisation temperature/° C. 29.4 t.b.d. V.sub.10 (20° C.)/V 24.2 t.b.d. V.sub.50 (20° C.)/V 39.5 t.b.d. V.sub.90 (20° C.)/V 50.3 t.b.d. V.sub.100 (20° C.)/V 57 t.b.d. ΔV.sub.50 (20° C.)/V 1.10 t.b.d. τ.sub.on (20° C.)/ms 2.94 t.b.d. τ.sub.off (20° C.)/ms 1.77 t.b.d. Memory 1.01 t.b.d. Remarks: t.b.d.: to be determined