Liquid crystal medium and liquid crystal display

Abstract

The instant invention relates to mesogenic media exhibiting a blue phase, comprising one or both components selected from the two following components, components A and B, component A, comprising one or more compounds selected from the group of compounds of formula I-M, ##STR00001##
and component B, consisting of one or more compounds selected from the group of compounds of formula I-U, ##STR00002##
wherein the parameters are as specified in the text, preferably stabilized by a polymer, and their use in electro-optical light modulation elements and their respective use in displays, as well as to such displays.

Claims

1. A mesogenic medium exhibiting a blue phase, comprising component A, component B, or a combination thereof, wherein: component A consists of one or more compounds of formula I-M ##STR00170## 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 each 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, L.sup.1 is H or F, X.sup.1 is F, CN or CF.sub.3, 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; and component B consists of one or more compounds of formula I-U ##STR00171## wherein R.sup.1, L.sup.1 and X.sup.1 have the respective meanings given above; and wherein said medium further comprises one or more compounds selected from formulae I-N and I-T ##STR00172## 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, n is 0 or 1, and L.sup.1 is in each case independently of one another H or F; wherein said medium exhibits a blue phase, and wherein said medium further comprises one or more chiral dopants.

2. The mesogenic medium according claim 1, wherein said medium comprises component A.

3. The mesogenic medium according claim 1, wherein said medium comprises component B.

4. The mesogenic medium according to claim 1, wherein said medium further comprises one or more compounds selected from formulae I-A and I-E ##STR00173## ##STR00174## 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, n is 0 or 1, and L.sup.01 to L.sup.03, L.sup.11 and L.sup.12 are each independently of one another H or F.

5. The mesogenic medium according to claim 1, wherein said medium further comprises one or more compounds of formula II ##STR00175## wherein L.sup.21 to L.sup.23 are each, independently of each other, H or F, CF.sub.3/F is CF.sub.3 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 each 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 each, independently of each other, F, Cl or CN, and alternatively one of them may be H, R.sup.01 and R.sup.02 are each, independently of each other, H or alkyl with 1 to 12 C-atoms.

6. The mesogenic medium according to claim 1, wherein said medium further comprises one or more compounds of formula III ##STR00176## wherein CF.sub.3/F is CF.sub.3 or F, 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.

7. The mesogenic medium according to claim 1, wherein said medium further comprises one or more compounds selected from the group of compounds of formulae IV and V ##STR00177## 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 each 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, ##STR00178## is ##STR00179## n and m are each, independently of one another, 0 or 1.

8. The mesogenic medium according to claim 1, wherein said medium further comprises a polymerizable component, which comprises one or more polymerizable compounds.

9. The mesogenic medium according to claim 1, wherein said medium further comprises one or more compounds of formula M1 ##STR00180## wherein: P.sup.1 and P.sup.2 are each, independently of one another, a polymerizable group, Sp.sup.1 and Sp.sup.2 are 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 is 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, are each optionally 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 are each optionally replaced by F, Cl, CN or P.sup.1-Sp.sup.1-, R.sup.0, R.sup.00 are each, at each occurrence independently of one another, H or alkyl having 1 to 12 C-atoms, R.sup.y and R.sup.z are each, independently of one another, H, F, CH.sub.3 or CF.sub.3, L is 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 is 0, 1, 2, 3 or 4.

10. The mesogenic medium according to claim 9, wherein said medium further comprises one or more compounds of formula M2 ##STR00181## wherein P.sup.1, P.sup.2, Sp.sup.1, Sp.sup.2, L and r have the meanings given in claim 9.

11. A method of stabilization of a mesogenic medium, comprising subjecting the polymerizable compounds of said medium according to claim 8 to polymerization.

12. A stabilized mesogenic medium obtained by the polymerization the polymerizable compounds constituents of said medium according to claim 8.

13. A light modulation element comprising a medium according to claim 1.

14. An electro-optical display comprising a medium according to claim 1.

15. A method of modulating light comprising modulating light with the light modulation element according to claim 13.

16. The mesogenic medium according to claim 1, wherein said medium contains components A and/or B in a total concentration of 10%-45% by weight.

17. The mesogenic medium according to claim 1, wherein said medium contains components A and/or B in a total concentration of 15%-45% by weight.

18. The mesogenic medium according to claim 1, wherein said medium contains components A and/or B in a total concentration of 20%-45% by weight.

19. The mesogenic medium according to claim 1, wherein said medium contains components A and/or B in a total concentration of 25%-45% by weight.

20. The mesogenic medium according to claim 1, wherein said medium contains 15%-35% by weight of one or more compounds of formula I-M, and/or 10% to 25% by weight of one or more compounds of formula I-U.

21. The mesogenic medium according to claim 1, wherein said medium contains one compound or more compounds of formula I-T.

22. The mesogenic medium according to claim 21, wherein said medium contains one compound or more compounds of formula I-T in a total concentration of 5% to 60% by weight.

23. The mesogenic medium according to claim 1, wherein said medium contains one compound or more compounds of formula I-N.

24. The mesogenic medium according to claim 23, wherein said medium contains one compound or more compounds of formula I-N in a total concentration of 5% to 40% by weight.

25. The mesogenic medium according to claim 1, wherein said medium contains one or more chiral compounds with a HTP of ≧20 μm−1.

26. The mesogenic medium according to claim 25, wherein said medium contains said one or more chiral compounds with a HTP of ≧20 μm−1 in a concentration of 1% to 20% by weight.

27. An electro-optical display comprising a medium according to claim 1, wherein said display operates at a temperature at which the medium is in said blue phase.

28. A method of stabilizing the blue phase of said medium according to claim 1, said process comprising: combining the medium with one or more chiral dopants and with one or more reactive compounds, holding the medium at a temperature at which the medium is in the blue phase, and maintaining this temperature while said one or more reactive compounds are polymerized.

29. The mesogenic medium according to claim 1, further comprising one or more compounds of ##STR00182## ##STR00183## ##STR00184## P.sup.a, P.sup.b each, independently of one another, are a polymerizable group, Sp.sup.a, Sp.sup.b each, independently of one another, denote a spacer group, and s1, s2 each, independently of one another, denote 0 or 1.

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) ##STR00154##

(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, and a solution of 52.0 g (0.300 mol) of 4-bromophenol in 200 ml of dichloromethane 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 dichloromethane is subsequently added dropwise. 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 dichloromethane, and the combined org. phases are dried over sodium sulfate. 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. .sup.19F-NMR (CDCl.sub.3, 235 MHz)

(7) δ=−63.1 ppm (t, J=26.7 Hz, 2 F, —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

(8) ##STR00155##

(9) 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 sulfate, 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

(10) ##STR00156##

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

(12) 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)phenoxyl]difluoromethyl}-3,5-difluoro-phenyl)hexyl acrylate

(13) ##STR00157##

(14) 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 dichloromethane, and a solution of 17.3 g (112 mmol) of EDC in 75 ml of dichloromethane is added dropwise 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 dichloromethane, giving 6-(4-{[4-(6-acryloyloxyhexyl)phenoxy]difluoromethyl}-3,5-difluorophenyl)hexyl acrylate as a colourless oil.

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

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

(17) 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, 2 H, 2 CH.sub.2═CH—OCO—), 6.39 (2 CHH═CH—OCO—), 6.78 (d, J=10.0 Hz, 2H, Ar—H), 7.15 (m.sub.c, 4 H, Ar—H). .sup.19F-NMR (CDCl.sub.3, 235 MHz)

(18) 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).

(19) Analogously the following reactive compounds are obtained

(20) ##STR00158##

(21) Phase behaviour: to be determined.

(22) ##STR00159##

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

(24) ##STR00160##

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

(26) ##STR00161##

(27) Phase behaviour: to be determined.

(28) ##STR00162##

(29) Phase behaviour: to be determined.

(30) ##STR00163##

(31) Phase behaviour: to be determined.

(32) ##STR00164##

(33) Phase behaviour: to be determined.

(34) ##STR00165##

(35) Phase behaviour: C 128° C. I.

(36) ##STR00166##

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

Example 1

(38) 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.

(39) TABLE-US-00007 Composition and properties liquid crystal mixture M-1 Composition Compound No. Abbreviation Conc./mass-% 1 UM-3-N 12.0 2 MUU-4-N 14.0 3 MUU-5-N 14.0 4 GUUQU-3-N 10.0 5 GUQGU-2-T 10.0 6 GUQGU-3-T 10.0 7 GUQGU-5-T 10.0 8 DUUQU-4-F 10.0 9 DUUQU-5-F 10.0 Σ 100.0 Physical Properties T(N, I) = 69° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε.sub.⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

(40) 3.8%, respectively 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 mixtures are filled into an electro optical test cells with inter-digital electrodes on one substrate side.

(41) 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.

(42) Appropriate Concentrations

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

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

(45) ##STR00167##

(46) and

(47) c) alternatively of one of the two reactive mesogenic compounds of the formulae RM-1

(48) ##STR00168##
and RM-2

(49) ##STR00169##
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.

(50) 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 re-characterised.

(51) Detailed Description of the Polymerisation

(52) 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.

(53) 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.

(54) 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.

(55) 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.

(56) 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.

(57) Electro-Optical Characterisation

(58) 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.

(59) 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.

(60) 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).

(61) 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.

(62) 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.

(63) 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.

(64) 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 T.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.

(65) 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.

(66) 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).

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

(68) TABLE-US-00008 Sample 1.1 1.2 Constituent Concentration/% M-1 86.6 86.6 R-5011 4.2 4.2 RM-C 5.75 6.0 RM-1 0.0 0.0 RM-2 3.25 3.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(70) 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 37.4 37.3 Polymerisation temperature/° C. 37.9 37.8 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 31 32 ΔV.sub.50 (20° C.)/V 1.8 1.2 τ.sub.on (20° C.)/ms 3.57 3.62 τ.sub.off (20° C.)/ms 2.34 2.34 Remark: t.b.d.: to be determined

(71) 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.

(72) The polymer-stabilised media M-1-1 and M-1-2, 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 and M-1-2 according to the invention, which indicates a very good stabilisation of the blue phase.

(73) 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

(74) 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.

(75) TABLE-US-00010 Composition and properties liquid crystal mixture C-1 Composition Compound No. Abbreviation Conc./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°, 1 kHz) = 14.8 Δε(20°, 1 kHz) = 212 γ.sub.1(30° C.) = 763 mPa .Math. s

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

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

(78) TABLE-US-00011 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

(79) 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.

(80) TABLE-US-00012 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⊥(20°, 1 kHz) = 12.9 Δε(20°, 1 kHz) = 277.8

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

(82) TABLE-US-00013 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

(83) 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.

(84) TABLE-US-00014 Composition and properties liquid crystal mixture M-2 Composition Compound Conc./ No. Abbreviation mass-% 1 MUU-4-N 15.0 2 MUU-5-N 15.0 3 GUQU-2-N 8.0 4 GUQU-3-N 9.0 5 GUQGU-2-T 8.0 6 GUQGU-3-T 9.0 7 GUQGU-5-T 8.0 8 DUUQU-3-F 8.0 9 DUUQU-4-F 10.0 10  DUUQU-5-F 10.0 Σ 100.0 Physical Properties T(N, I) = 69.5° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(86) TABLE-US-00015 Sample 2.1 2.2 Constituent Concentration/% M-2 86.6 86.6 R-5011 4.2 4.2 RM-C 5.75 6.0 RM-1 0.0 0.0 RM-2 3.25 3.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(88) TABLE-US-00016 Mixture M-2-1 M-2-2 Host M-2 M-2 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 35.1 37.2 Polymerisation temperature/° C. 35.6 37.7 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 35 31 ΔV.sub.50 (20° C.)/V 1.1 1.2 τ.sub.on (20° C.)/ms 2.48 4.41 τ.sub.off (20° C.)/ms 1.87 3.9 Remark: t.b.d.: to be determined

Example 3

(89) 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.

(90) TABLE-US-00017 Composition and properties liquid crystal mixture M-3 Composition Compound Conc./ No. Abbreviation mass-% 1 MUU-4-N 11.0 2 MUU-5-N 11.0 3 GUQU-2-N 8.0 4 GUQU-3-N 8.0 5 GUUQU-3-N 10.0 6 GUQGU-2-T 8.0 7 GUQGU-3-T 10.0 8 GUQGU-5-T 10.0 9 DUUQU-3-F 6.0 10  DUUQU-4-F 9.0 11  DUUQU-5-F 9.0 Σ 100.0 Physical Properties T(N, I) = 78° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(92) TABLE-US-00018 Sample 3.1 3.2 Constituent Concentration/% M-3 86.6 86.6 R-5011 4.2 4.2 RM-C 5.75 6.0 RM-1 0.0 0.0 RM-2 3.25 3.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(94) TABLE-US-00019 Mixture M-3-1 M-3-2 Host M-3 M-3 Reactive mesogen RM-2 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. 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 t.b.d. t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. τ.sub.on (20° C.)/ms t.b.d. t.b.d. τ.sub.off (20° C.)/ms t.b.d. t.b.d. Remark: t.b.d.: to be determined

Example 4

(95) 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.

(96) TABLE-US-00020 Composition and properties liquid crystal mixture M-4 Composition Compound Conc./ No. Abbreviation mass-% 1 UM-3-N 11.0 2 MUU-4-N 14.0 3 MUU-5-N 14.0 4 GUUQU-3-N 10.0 5 GUQGU-2-T 9.0 6 GUQGU-3-T 9.0 7 GUQGU-5-T 9.0 8 DUUQU-3-F 6.0 9 DUUQU-4-F 9.0 10  DUUQU-5-F 9.0 Σ 100.0 Physical Properties T(N, I) = 70° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(98) TABLE-US-00021 Sample 4.1 4.2 Constituent Concentration/% M-4 85.6 85.6 R-5011 4.2 4.2 RM-C 6.5 6.5 RM-1 0.0 3.5 RM-2 3.5 0.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(100) TABLE-US-00022 Mixture M-4-1 M-4-2 Host M-4 M-4 Reactive mesogen RM-2 RM-1 Transition point before the polymerisation 35.7 t.b.d. Polymerisation temperature/° C. 36.2 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 32 t.b.d. ΔV.sub.50 (20° C.)/V 1.1 t.b.d. Memory effect (20° C.) 0.97 t.b.d. τ.sub.on (20° C.)/ms 2.91 t.b.d. τ.sub.off (20° C.)/ms 1.80 t.b.d. Remark: t.b.d.: to be determined

Example 5

(101) 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.

(102) TABLE-US-00023 Composition and properties liquid crystal mixture M-5 Composition Compound Conc./ No. Abbreviation mass-% 1 MUU-3-N 6.0 2 MUU-4-N 15.0 3 MUU-5-N 15.0 4 MUQU-2-F 10.0 5 MUQU-3-F 10.0 6 GUUQU-3-N 11.0 7 DUUQU-3-F 8.0 8 DUUQU-4-F 10.0 9 DUUQU-5-F 10.0 10  DPGU-4-F 5.0 Σ 100.0 Physical Properties T(N, I) = 70° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(104) TABLE-US-00024 Sample 5.1 5.2 Constituent Concentration % M-5 88.0 88.0 R-5011 3.8 3.8 RM-C 5.0 5.0 RM-1 0.0 3.0 RM-2 3.0 0.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(106) TABLE-US-00025 Mixture M-5-1 M-5-2 Host M-5 M-5 Reactive mesogen RM-2 RM-1 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. 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 t.b.d. t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. Memory effect (20° C.) t.b.d. t.b.d. Remark: t.b.d.: to be determined

Example 6

(107) The following liquid crystalline mixture M-6 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(108) TABLE-US-00026 Composition and properties liquid crystal mixture M-6 Composition Compound No. Abbreviation Conc./mass-% 1 MUU-4-N 12.0 2 MUU-5-N 12.0 3 GUQU-2-N 10.0 4 GUQU-3-N 10.0 5 GUQU-5-N 10.0 6 GUUQU-3-N 10.0 7 GUQGU-2-T 8.0 8 GUQGU-3-T 8.0 9 DUUQU-4-F 10.0 10 DUUQU-5-F 10.0 Σ 100.0 Physical Properties T(N, I) = 70° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε.sub.⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(110) TABLE-US-00027 Sample 6.1 6.2 Constituent Concentration/% M-6 85.6 86.6 R-5011 4.2 4.2 RM-C 6.5 6.0 RM-1 0.0 0.0 RM-2 3.5 3.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(112) TABLE-US-00028 Mixture M-6-1 M-6-2 Host M-6 M-6 Reactive mesogen RM-2 RM-2 Transition point before the polymerisation 35.4 36.3 Polymerisation temperature/° C. 35.9 36.8 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 29 28 ΔV.sub.50 (20° C.)/V 1.5 1.9 Memory effect (20° C.) 1.04 1.05 Remark: t.b.d.: to be determined

Example 7

(113) The following liquid crystalline mixture M-7 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(114) TABLE-US-00029 Composition and properties liquid crystal mixture M-7 Composition Compound No. Abbreviation Conc./mass-% 1 UM-4-N 10.0 2 MUU-4-N 10.0 3 MUU-5-N 10.0 4 PZG-3-N 8.0 5 GUUQU-3-N 10.0 6 GUUQU-4-N 10.0 7 GUUQU-5-N 10.0 8 PUQGU-2-T 8.0 9 PUQGU-3-T 8.0 10 PUQGU-4-T 8.0 11 PUQGU-5-T 8.0 Σ 100.0 Physical Properties T(N, I) = 74.5° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε.sub.⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(116) TABLE-US-00030 Sample 7.1 7.2 Constituent Concentration/% M-7 87.0 87.0 R-5011 3.8 3.8 RM-C 6.0 6.0 RM-1 0.0 3.0 RM-2 3.0 0.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(118) TABLE-US-00031 Mixture M-7-1 M-7-2 Host M-7 M-7 Reactive mesogen RM-2 RM-1 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. 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 t.b.d. t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. Memory effect (20° C.) t.b.d. t.b.d. Remark: t.b.d.: to be determined

Example 8

(119) The following liquid crystalline mixture M-8 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(120) TABLE-US-00032 Composition and properties liquid crystal mixture M-8 Composition Compound No. Abbreviation Conc./mass-% 1 UMU-5-N 8.0 2 UMU-6-N 8.0 3 MUU-4-N 10.0 4 MUU-5-N 10.0 5 GUQU-3-N 12.0 6 GUQU-3-N 12.0 7 GUQGU-2-T 9.0 8 GUQGU-3-T 9.0 9 DUUQU-4-F 9.0 10 DUUQU-5-F 9.0 11 DPGU-4-F 4.0 Σ 100.0 Physical Properties T(N, I) = 68° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε.sub.⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(122) TABLE-US-00033 Sample 8.1 8.2 Constituent Concentration/% M-8 87.0 87.0 R-5011 3.8 3.8 RM-C 6.0 6.0 RM-1 0.0 3.0 RM-2 3.0 0.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(124) TABLE-US-00034 Mixture M-8-1 M-8-2 Host M-8 M-8 Reactive mesogen RM-2 RM-1 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. 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 t.b.d. t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. Memory effect (20° C.) t.b.d. t.b.d. Remark: t.b.d.: to be determined

Example 9

(125) The following liquid crystalline mixture M-9 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(126) TABLE-US-00035 Composition and properties liquid crystal mixture M-9 Composition Compound No. Abbreviation Conc./mass-% 1 UMU-4-N 13.6 2 GUQU-2-N 9.7 3 GUQU-3-N 9.7 4 GUQU-5-N 7.8 5 GUUQU-3-N 9.7 6 GUQGU-2-T 9.7 7 GUQGU-3-T 8.7 8 GUQGU-5-T 8.7 9 DUUQU-4-F 9.7 10 DUUQU-5-F 9.7 11 DPGU-4-F 3.0 Σ 100.0 Physical Properties T(N, I) = 71.5° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε.sub.⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(128) TABLE-US-00036 Sample 9.1 9.2 Constituent Concentration/% M-9 87.0 87.0 R-5011 4.2 4.2 RM-C 6.5 6.5 RM-1 0.0 3.5 RM-2 3.5 0.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(130) TABLE-US-00037 Mixture M-9-1 M-9-2 Host M-9 M-9 Reactive mesogen RM-2 RM-1 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. 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 t.b.d. t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. Memory effect (20° C.) t.b.d. t.b.d. Remark: t.b.d.: to be determined

Example 10

(131) The following liquid crystalline mixture M-10 is prepared and investigated with respect to its general physical properties. The composition and properties are given in the following table.

(132) TABLE-US-00038 Composition and properties liquid crystal mixture M-10 Composition Compound No. No. Abbreviation Conc./mass-% 1 UMU-4-N 14.0 2 GUQU-2-N 10.0 3 GUQU-3-N 10.0 4 GUQU-5-N 8.0 5 GUUQU-3-N 10.0 6 GUQGU-2-T 10.0 7 GUQGU-3-T 9.0 8 GUQGU-5-T 9.0 9 DUUQU-4-F 10.0 10 DUUQU-5-F 10.0 Σ 100.0 Physical Properties T(N, I) = 68° C. n.sub.o(20° C., 589 nm) = t.b.d. Δn(20° C., 589 nm) = t.b.d. ε.sub.⊥(20°, 1 kHz) = t.b.d. Δε(20°, 1 kHz) = t.b.d. γ.sub.1(20° C.) = t.b.d. mPa .Math. s Remark: t.b.d.: to be determined

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

(134) TABLE-US-00039 Sample 10.1 10.2 Constituent Concentration/% M-10 87.0 87.0 R-5011 4.2 4.2 RM-C 6.5 6.5 RM-1 0.0 3.5 RM-2 3.5 0.0 IRG-651 ® 0.2 0.2 Σ 100.0 100.0

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

(136) TABLE-US-00040 Mixture M-10-1 M-10-2 Host M-10 M-10 Reactive mesogen RM-2 RM-1 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. 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 t.b.d. t.b.d. ΔV.sub.50 (20° C.)/V t.b.d. t.b.d. Memory effect (20° C.) t.b.d. t.b.d. Remark: t.b.d.: to be determined