Liquid crystal medium and liquid display

Abstract

Mesogenic media comprising one or more compounds of formulae I or II ##STR00001##
preferably mesogenic media showing a blue phase, preferably stabilized by a polymer, and their use in electro-optical light modulation elements and their respective use in displays, as well as such devices.

Claims

1. A mesogenic medium comprising (1) 40-80% by weight of four compounds of formula I, and 4 to 8% by weight of two compounds of formula II-3 ##STR00141## wherein L.sup.1 is F, R.sup.1 and R.sup.2 are, independently of each other, straight chain or branched alkyl having 1-20 C atoms 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, SiR.sup.01R.sup.02, CO, COO, OCO, OCOO, SCO, COS, CY.sup.01CY.sup.02 or CC 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, (2) one or more polymerizable compounds that is a reactive mesogen of the formula RM-C ##STR00142## a reactive mesogenic compound of the formula RM-1 ##STR00143## or RM-2 ##STR00144## (3) one or more compounds of formula III ##STR00145## wherein R.sup.3 has the meaning given for R.sup.1, (4) one or more compounds of formula IV ##STR00146## wherein R.sup.4 is alkyl with 1-20 C atoms, 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, CO, COO, OCO, OCOO, SCO, COS or CC in such a manner that O and/or S atoms are not linked directly to one another, ##STR00147## and n is 1, and (5) two compounds of formula V ##STR00148## wherein R.sup.5 is alkyl with 1-20 C atoms, 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, CO, COO, OCO, OCOO, SCO, COS or CC in such a manner that O and/or S atoms are not linked directly to one another, L.sup.5 is F, and m is 0 said medium containing a chiral dopant which produces, in the medium, a blue phase, of the formula ##STR00149##

2. A method of stabilization of a mesogenic medium, comprising subjecting a medium according to claim 1 to polymerization of its polymerizable constituents.

3. A mesogenic medium stabilized by the polymerization of polymerizable constituents of a medium according to claim 1.

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

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

6. The medium according to claim 1, wherein R.sup.1 and R.sup.2 are each independently alkyl substituted by F.

7. The medium according to claim 1, wherein R.sup.4 and R.sup.5 are each independently alkyl substituted by F.

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 m.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) ##STR00125##

(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.

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

(8) =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, ArF).

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

(9) ##STR00126##

(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 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

(11) ##STR00127##

(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 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) =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, ArF).

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

(15) ##STR00128##

(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 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.

(17) Phase behaviour: T.sub.g-71 C. 13 l.

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

(19) =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-ArCH.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 CHHCHCOO), 6.11 (m.sub.c, 2 H, 2 CH.sub.2CHCOO), 6.39 (2 CHHCHCOO), 6.78 (d, J=10.0 Hz, 2H, ArH), 7.15 (m.sub.c, 4 H, ArH).

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

(21) =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, ArF).

(22) Analogously the following reactive compounds are obtained

(23) ##STR00129##
Phase behaviour: to be determined.

(24) ##STR00130##
Phase behaviour: T.sub.g-66 C. I.

(25) ##STR00131##
Phase behaviour: T.sub.g-69 C. I.

(26) ##STR00132##
Phase behaviour: to be determined.

(27) ##STR00133##
Phase behaviour: to be determined.

(28) ##STR00134##
Phase behaviour: to be determined.

(29) ##STR00135##
Phase behaviour: to be determined.

(30) ##STR00136##
Phase behaviour: C 128 C. l.

(31) ##STR00137##
Phase behaviour: T.sub.g-59 C. N 28.5 C. I.

Example 1

(32) 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.

(33) TABLE-US-00007 Composition and properties liquid crystal mixture M-1 Composition Compound Conc./ No. Abbreviation mass-% 1 PGU-4-T 4.0 2 PGU-5-T 3.0 3 DPGU-4-F 8.0 4 GUQU-3-F 7.0 5 GUQU-4-F 6.0 6 GUQGU-3-F 8.0 7 GUQGU-4-F 6.0 8 GUQGU-5-F 4.0 9 GUQGU-2-T 12.0 10 GUQGU-3-T 12.0 11 GUQGU-4-T 12.0 12 GUQGU-5-T 12.0 13 GUUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 71 C. n(20 C., 589 nm) = 0.1929 (20, 1 kHz) = 201.5 k.sub.11(20 C.) = 21.98 pN

(34) 5% of the chiral agent R-5011 are solved in the achiral liquid crystal mixture M-1 and the electro-optical response of resultant mixture in an IPS-type cell is investigated. The mixture is filled into an electro optical test cell with inter-digital electrodes on one substrate side. The electrode width is 10 m, the distance between adjacent electrodes is 10 m and the cell gap is also 10 m. This test cell is evaluated electro-optically between crossed polarisers.

(35) Appropriate Concentrations

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

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

(38) ##STR00138##
and
c) alternatively of one of the two reactive mesogenic compounds of the formulae RM-1

(39) ##STR00139##
and RM-2

(40) ##STR00140##
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.

(41) 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.

(42) Detailed Description of the Polymerisation

(43) 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 22.5 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.

(44) 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.

(45) 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.

(46) 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.

(47) 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.

(48) Electro-Optical Characterisation

(49) 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.

(50) 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.

(51) 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) 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).

(52) 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.

(53) 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.

(54) 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.2T.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.

(55) In the second part of the measurement, the response times during switching on and off (.sub.on, .sub.off) are determined. The response time .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 .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.

(56) 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 T.sub.50 and V.sub.50 respectively.

(57) 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).

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

(59) TABLE-US-00008 Sample 1 2 Constituent Concentration/% M-1 87.8 88.0 R-5011 4.0 3.8 RM-C 5.0 5.0 RM-1 3.0 0.0 RM-2 0.0 3.0 IRG-651 0.2 0.2 100.0 100.0

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

(61) TABLE-US-00009 Mixture M-1-1 M-1-2 Host C-1 Reactive mesogen Measurement values (20 C.) RM-1 RM-2 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 26.6. 21.3 V.sub.90 (20 C.)/V 49.9 42.0 V.sub.50 (20 C.)/V 3.28 2.46 Contrast, switching on t.b.d. t.b.d. Contrast, switching off t.b.d. t.b.d. Memory effect 1.06 1.07 Remarks: t.b.d.: to be determined

(62) 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 (cf. above for details).

(63) The polymer-stabilised liquid-crystalline media exhibit a blue phase over a broad temperature range.

(64) The polymer-stabilised medium M1, prepared using the monomer (1) according to the invention, exhibits a reduction in hysteresis (V.sub.50) and good contrast on 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 medium M1 according to the invention, which means very good stabilisation of the blue phase.

(65) 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 and 2

(66) 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.

(67) TABLE-US-00010 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 605 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 11.0 100.0 Physical Properties T(N, I) = 71 C. n(20 C., 589 nm) = 0.1515 (20, 1 kHz) = 224 1(30 C.) = 763 mPa .Math. s

(68) This mixture is treated and investigated as described in detail under example 1 above. The results are compiled in the following table.

(69) TABLE-US-00011 Mixture C-1-1 C-1-2 Host C-1 Reactive mesogen Measurement values (20 C.) RM-1 RM-2 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.90 (20 C.)/V 58.6 42.0 V.sub.100 (20 C.)/V 67.0 47.9 V.sub.50 (20 C.)/V 4.73 1.90 Contrast, switching on 285 206 Contrast, switching off 276 208 Memory effect 1.04 0.99 Remarks: t.b.d.: to be determined

Example 2

(70) TABLE-US-00012 Composition and properties liquid crystal mixture M-2 Composition Compound Conc./ No. Abbreviation mass-% 1 PGU-4-T 4.0 2 PGU-5-T 3.0 3 DPGU-4-T 8.0 4 GUQU-3-F 7.0 5 GUQU-4-F 6.0 6 GUQGU-3-F 8.0 7 GUQGU-4-F 6.0 8 GUQGU-5-F 4.0 9 GUQGU-2-T 12.0 10 GUQGU-3-T 12.0 11 GUQGU-4-T 12.0 12 GUQGU-5-T 12.0 13 AUUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 72 C. n(20 C., 589 nm) = 0.1879 (20, 1 kHz) = 188.6

Example 3

(71) TABLE-US-00013 Composition and properties liquid crystal mixture M-3 Composition Compound Conc./ No. Abbreviation mass-% 1 PGU-5-T 7.0 2 DPGU-4-F 8.0 3 GUQU-3-F 7.0 4 GUQU-4-F 6.0 5 GUQGU-3-F 8.0 6 GUQGU-4-F 6.0 7 GUQGU-5-F 4.0 8 GUQGU-2-T 12.0 9 GUQGU-3-T 12.0 10 GUQGU-4-T 12.0 11 GUQGU-5-T 12.0 12 AUUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 71.5 C. n(20 C., 589 nm) = 0.1886 (20, 1 kHz) = 181.9 k.sub.1120 C.) = 16.28 pN

Example 4

(72) TABLE-US-00014 Composition and properties liquid crystal mixture M-4 Composition Compound Conc./ No. Abbreviation mass-% 1 DPGU-4-F 8.0 2 GUQU-3-F 6.0 3 GUQU-4-F 6.0 4 GUQU-5-F 6.0 5 GUQGU-3-F 7.0 6 GUQGU-4-F 3.0 7 GUQGU-5-F 3.0 8 GUQGU-2-T 12.0 9 GUQGU-3-T 13.0 10 GUQGU-4-T 15.0 11 GUQGU-5-T 15.0 12 GUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 62.5 C. n(20 C., 589 nm) = 0.1809 (20, 1 kHz) = 157.8

Example 5

(73) TABLE-US-00015 Composition and properties liquid crystal mixture M-5 Composition Compound Conc./ No. Abbreviation mass-% 1 DPGU-4-F 3.0 2 GUQU-3-F 6.0 3 GUQU-4-F 8.0 4 GUQU-5-F 10.0 5 GUQGU-3-F 4.0 6 GUQGU-4-F 5.0 7 GUQGU-5-F 7.0 8 GUQGU-2-T 12.0 9 GUQGU-3-T 12.0 10 GUQGU-4-T 14.0 11 GUQGU-5-T 13.0 12 GUUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 59 C. n(20 C., 589 nm) = 0.1779 (20, 1 kHz) = 173.7 .sub.1(30 C.) = 596 mPa .Math. s

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

(75) TABLE-US-00016 Sample 1 2 3 Constituent Concentration/% M-5 87.0 89.0 87.4 R-5011 3.8 3.8 3.4 RM-C 5.0 4.0 5.0 RM-2 4.0 3.0 4.0 IRG-651 0.2 0.2 0.2 100.0 100.0 100.0 M-1 87.8 R-5011 4.0 RM-C 5.0 RM-1 0.0 RM-2 3.0 IRG-651 0.2 Mixture M-5-1 M-5-2 Host M-5 Reactive mesogen Measurement values (20 C.) RM-1 RM-2 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. 25.3 V.sub.90 (20 C.)/V t.b.d. 49.5 V.sub.50 (20 C.)/V t.b.d. 1.85 Contrast, switching on t.b.d. t.b.d. Contrast, switching off t.b.d. t.b.d. Memory effect t.b.d. 1.00 Remarks: t.b.d.: to be determined

Example 6

(76) TABLE-US-00017 Composition and properties liquid crystal mixture M-6 Composition Compound Conc./ No. Abbreviation mass-% 1 DPGU-4-F 7.0 2 GUQU-3-F 7.0 3 GUQU-4-F 7.0 4 GUQU-5-F 7.0 5 GUQGU-3-F 5.0 6 GUQGU-4-F 3.0 7 GUQGU-5-F 3.0 8 GUQGU-2-T 12.0 9 GUQGU-3-T 12.0 10 GUQGU-4-T 13.0 11 GUQGU-5-T 15.0 12 GUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 56.5 C. ne(20 C., 589 nm) = 1.6616 n(20 C., 589 nm) = 0.1743 (20, 1 kHz) = 139.6

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

(78) TABLE-US-00018 Sample 1 2 Constituent Concentration/% M-6 88.0 88.0 R-5011 3.8 3.8 RM-C 5.0 5.0 RM-1 3.0 0.0 RM-2 0.0 3.0 IRG-651 0.2 0.2 100.0 100.0 Mixture M-6-1 M-6-2 Host M-6 Reactive mesogen Measurement values (20 C.) RM-1 RM-2 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 31.8 29.9 V.sub.90 (20 C.)/V 62.0 58.1 V.sub.100 (20 C.)/V 70.1 65.7 V.sub.50 (20 C.)/V 3.29 2.44 Contrast, switching on t.b.d. t.b.d. Contrast, switching off t.b.d. t.b.d. Memory effect 1.04 1.02 Remarks: t.b.d.: to be determined

Example 7

(79) TABLE-US-00019 Composition and properties liquid crystal mixture M-7 Composition Compound Conc./ No. Abbreviation mass-% 1 DPGU-4-F 5.0 2 GUQU-3-F 7.0 3 GUQU-4-F 6.0 4 GUQU-5-F 7.0 5 GUQGU-3-F 8.0 6 GUQGU-4-F 6.0 7 GUQGU-5-F 4.0 8 GUQGU-2-T 12.0 9 GUQGU-3-T 12.0 10 GUQGU-4-T 14.0 11 GUQGU-5-T 13.0 12 GUUQU-5-N 6.0 100.0 Physical Properties T(N, I) = 66 C. n(20 C., 589 nm) 0.1929 (20, 1 kHz) 201.5 k.sub.11(20 C.) = 21.98 pN

Example 8

(80) TABLE-US-00020 Composition and properties liquid crystal mixture M-8 Composition Compound Conc./ No. Abbreviation mass-% 1 DPGU-4-F 3.0 2 GUQU-3-F 8.0 3 GUQU-4-F 8.0 4 GUQU-5-F 8.0 5 GUQGU-3-F 7.0 6 GUQGU-4-F 5.0 7 GUQGU-5-F 4.0 8 GUQGU-2-T 12.0 9 GUQGU-3-T 12.0 10 GUQGU-4-T 14.0 11 GUQGU-5-T 13.0 12 GUQU-3-N 6.0 100.0 Physical Properties T(N, I) = 56.5 C. n(20 C., 589 nm) = 0.1781 (20, 1 kHz) = 179.7

Example 9

(81) TABLE-US-00021 Composition and properties liquid crystal mixture M-9 Composition Compound Conc./ No. Abbreviation mass-% 1 GUQU-3-F 5.0 2 GUQU-4-F 60 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 10.0 100.0 Physical Properties T(N, I) = 65 C. n(20 C., 589 nm) = 0.1859 (20, 1 kHz) = 277.8

(82) TABLE-US-00022 Mixture M-9-1 M-9-2 Host M-9 Reactive mesogen Measurement values (20 C.) RM-1 RM-2 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.90 (20 C.)/V t.b.d. 38.2 V.sub.100 (20 C.)/V t.b.d. 43.0 V.sub.50 (20 C.)/V t.b.d. 2.16 Contrast, switching on t.b.d. t.b.d. Contrast, switching off t.b.d. t.b.d. Memory effect t.b.d. 1.03 Remarks: t.b.d.: to be determined