Photoactive polymer materials

Abstract

The present invention relates to novel photoactive polymer materials and their use as orienting layer for liquid crystals, which are used for the production of non-structured and structured optical elements or electro-optical elements and multi-layer systems.

Claims

1. Polymer material which is a homopolymer and comprises repeating units of formula (I): ##STR00022## wherein M.sup.1 is a monomer unit selected from the group consisting of acrylate, methacrylate, ring A is unsubstituted phenylene or phenylene which is substituted with alkyl or alkoxy, ring B is phenylene, Y.sup.1, Y.sup.2 are —CO—O—; m is 1, and n is 0; ring C is unsubstituted phenylene or phenylene which is substituted with methoxy, ethoxy, propoxy or butoxy; S.sup.1 is a spacer unit S.sup.3; wherein S.sup.3 is —(CH.sub.2).sub.r—O—, wherein r is 10, 11 or 12; z is —O—, D is methyl, ethyl, propyl.

2. Process for the preparation of polymer material according to claim 1 comprising polymerising a monomer compound of formula (I′) ##STR00023## wherein M.sup.2 is acrylate, methacrylate; and S.sup.1, A, B, C, D, Y.sup.1, Y.sup.2, n, m and z have the meanings as described in claim 1.

3. Monomer compound of formula (I′): ##STR00024## wherein M.sup.2 is acrylate, methacrylate; ring A is unsubstituted phenylene or phenylene which is substituted with alkyl or alkoxy, ring B is phenylene, Y.sup.1, Y.sup.2 are —CO—O—; m is 1, and n is 0; ring C is unsubstituted phenylene or phenylene which is substituted with methoxy, ethoxy, propoxy or butoxy; S.sup.1 is a spacer unit S.sup.3; wherein S.sup.3 is —(CH.sub.2).sub.r—O—, wherein r is 10, 11 or 12; z is —O—, D is methyl, ethyl, propyl.

4. Composition comprising polymer material according to claim 1 and optionally a solvent selected from the group consisting of γ-butyrolactone, N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, methylethylketone (MEK), 1-methoxypropylacetate (MPA), and 1-methoxypropanol (MP).

5. Method of using polymer material according to claim 1, or a composition thereof, comprising providing the polymer material or the composition as an orienting layer for liquid crystals.

6. Method for the preparation of an orientation layer for liquid crystals comprising irradiating polymer material according to claim 1.

7. Orientation layers comprising polymer material according to claim 1.

8. Optical or electro-optical elements comprising polymer material according to claim 1.

9. Polymer material according to claim 1, wherein r is 11.

10. Polymer material according to claim 1, wherein r is 12.

11. Polymer material according to claim 9, wherein ring C is phenylene substituted with methoxy.

12. Polymer material according to claim 10, wherein ring C is phenylene substituted with methoxy.

13. Composition comprising polymer material according to claim 1 and a solvent selected from the group consisting of γ-butyrolactone, N,N-dimethylacetamide, N-methylpyrrolidone, N,N-dimethylformamide, methylethylketone (MEK), 1-methoxypropylacetate (MPA), and 1-methoxypropanol (MP).

Description

EXAMPLE 1

Poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-hexoxycarbonyl]-1-methyl-ethylene], which is 2-Propenoic acid, 2-methyl-,6-[4-[(1E)-3-methoxy-3-oxo-1-propen-1-yl]phenoxy]hexyl Ester, Homopolymer

(1) ##STR00014##

(2) 0.73 g (2.03 mmol) of 6-{4-[(1E)-3-methoxy-3-oxoprop-1-enyl]phenoxy}hexyl (2Z)-2-methylbut-2-enoate and 1.67 mg (0.01 mmol) of 2,2′-azo-bis-isobutyronitrile (AIBN) are dissolved in 4.1 ml of tetrahydrofuran (THF). The solution is flushed with a weak stream of argon for 15 minutes. Subsequently, the reaction vessel is sealed air-tight and heated to 60° C. After 24 hours the vessel is opened, the solution is diluted with 4 ml of THF and is added drop wise to 800 ml of diethyl ether at room temperature while stirring vigorously. The separated polymer is filtered off and dried at 60° C. in a water-jet vacuum. For further purification, the polymer is dissolved in 10 ml of dichloromethane and again precipitated in 80 ml of diethyl ether. This procedure is repeated until monomer is no longer detected by thin-layer chromatography. Filtration and drying at 60° C. in a vacuum gives 0.37 g of product poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-hexoxycarbonyl]-1-methyl-ethylene]; as a white powder with a glass stage at T.sub.g=11° C. and a decadic absorption maximum of λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm (ε=36000 l/mol cm).

(3) .sup.1H-NMR (in CDCl.sub.3): 1.730, 1.610, 1.562, 1.4-1 ppm (5×CH.sub.2 and CH.sub.3), 315 ppm (OOCH.sub.3), 3.89-3.88 ppm (2×OCH.sub.2), 6.27 and 6.23 and 7.60 and 7.56 ppm (CH═CH)

(4) The 6-[4-[(E)-2-Methoxycarbonyl-vinyl]-phenoxy]-hexyl 2-methyl-acrylate used as starting material is prepared according to the following procedure.

Methyl 3-(4-hydroxyphenyl)-acrylate

(5) ##STR00015##

(6) 51.2 g (312 mmol) of p-coumaric acid are dissolved in 330 ml of methanol and treated with 10 ml of concentrated sulphuric acid. The solution is heated under reflux for 2 hours. Subsequently the majority of the methanol (about 200 ml) is distilled off and the residue remaining behind was poured into 1.3 l of ice-water. The separated ester is filtered off under suction and washed in succession with cold water, with a small amount of cold NaHCO.sub.3 solution and again with cold water. Drying at 50° C. in a water-jet vacuum gives 51.1 g of methyl 3-(4-hydroxyphenyl)-acrylate in the form of a light brownish coloured powder.

Methyl (E)-3-[4-[6-hydroxyhexoxy]-phenyl]-acrylate

(7) ##STR00016##

(8) 30 g (168 mmol) of methyl 3-(4-hydroxyphenyl)-acrylate, 29 g (210 mmol) of anhydrous K.sub.2CO.sub.3 and a spatula tip of KI are placed in 200 ml of dimethylformamide. 17.95 g (185 mmol) of 6-chlorohexanol are added drop wise at 85° C. within 5 minutes while stirring. The batch is stirred at 85° C. for a further 3 days. Subsequently, the salts are filtered off and the filtrate is concentrated to dryness in a water-jet vacuum. 17.2 g of methyl (E)-3-[4-[6-hydroxyhexoxy]-phenyl]-acrylate are obtained in the form of white crystals after recrystallization from i-propanol.

6-[4-[(E)-2-Methoxycarbonyl-vinyl]-phenoxy]-hexyl 2-methyl-acrylate

(9) ##STR00017##

(10) 2.56 g (30 mmol) of methacrylic acid in 10 ml of THF are slowly added drop wise to a solution of 6.1 g (27 mmol) of methyl (E)-3-[4-[6-hydroxyhexoxy]-phenyl]-acrylate, 5.85 g (28.3 mmol) of N,N′-dicyclohexylcarbodiimide (DCC) and 0.37 g (3 mmol) of 4-dimethylamino-pyridine in 80 ml of tetrahydrofuran (THF). The batch is stirred at room temperature overnight. In order to complete the reaction there are added firstly a further 1.46 g (7.1 mmol) of DCC and, after stirring for one hour, a further 0.5 g (5.9 mmol) of methacrylic acid. The batch is stirred for a further 24 hours, filtered and the filtrate is extracted 3 times each time with 200 ml of 5% acetic acid and 200 ml of water. The ether phase is dried over Na.sub.2SO.sub.4, evaporated and the residue is recrystallized from cyclohexane. Subsequently, the still slightly impure product is filtered over a thin silica gel layer (eluent: diethyl ether/hexane=1:1). This gives 8.1 g of 6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-hexyl 2-methyl-acrylate as a white powder, having a melting point of 45-50° C. and a decadic absorption maximum of λ.sub.max. (in CH.sub.2Cl.sub.2)=310 nm (ε=37000 l/mol cm).

(11) The following polymers are synthesized in an analogous manner: poly [1-[6-[4-[(E)-2-ethoxycarbonyl-vinyl]-phenoxy]-hexoxycarbonyl]-1-methyl-ethylene]; poly [1-[3-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-propoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=306 nm poly [1-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-butoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=307 nm poly [1-[5-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-pentoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[7-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-heptoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-octoxycarbonyl]-1-methyl-ethylene]; T.sub.g=21.4° C.; poly [1-[9-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-undecoxycarbonyl]-1-methyl-ethylene]; poly [1-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-butoxycarbonyl]-1-methyl-ethylene]; T.sub.g=60° C.; λ.sub.max. (in CH.sub.2Cl.sub.2)=322.5 and 295.5 nm poly [1-[5-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-pentoxycarbonyl]-1-methyl-ethylene]; poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-hexoxycarbonyl]-1-methyl-ethylene]; T.sub.g=64° C.; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-octoxycarbonyl]-1-methyl-ethylene]; poly [1-[11-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-undecoxycarbonyl]-1-methyl-ethylene]; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-octoxy]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenyl carbonyloxy]-ethoxycarbonyl]-1-methyl-ethylene]; poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenyl carbonyloxy]-hexoxycarbonyl]-1-methyl-ethylene]; T.sub.g=29.8° C.; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenyl carbonyloxy]-octoxycarbonyl]-1-methyl-ethylene] poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-hexoxycarbonyl]-1-methyl-ethylene-co-[4-hydroxybutoxycarbonyl]-ethylene] poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2-octoxy-phenoxy]-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=323 nm (ε=17829 l/mol cm), poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-hexoxycarbonyl]-1-methyl-ethylene-co-[4-hydroxybutoxycarbonyl]-ethylene], T.sub.g=28.5° C.; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-(4-hexyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[1-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxy-phenoxy]-dec-1-ine-oxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=333 nm poly [1-[3-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-(2-(4-butyloxyphenyl)-propoxycarbonyl)]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=308 nm poly [1-[[3-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-((2-(4-butyloxyphenyl)-propyl)-1-carbamat-ethoxycarbonyl)]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[[3-[(E)-2-methoxycarbonyl-vinyl]-2-methoxy-phenoxy]-(2-(4-butyloxyphenyl)-propyl)-carbamat-ethoxycarbonyl)]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=322 nm poly [1-[6-[4-[(E)-2-(adamantylmethoxycarbonyl-vinyl]-2-methoxy-phenoxy]-hexoxycarbonyl]-1-methyl-ethylene]; T.sub.g=70° C.; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-(2-(8-(5,5-dimethyl-1,3-dioxan-2-yl) octyl)-propoxycarbonyl)]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=308 nm poly [1-[[3-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-(3(2-(8-(5,5-dimethyl-1,3-dioxan-2-yl)-propyl)-carbamat-ethoxycarbonyl)]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-2-(1-butyl-4-hexyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxy-phenoxy]-hex-1-ine-oxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=330 nm poly [1-[[1-[(E)-2-methoxycarbonyl-vinyl]-phenoxyl]propyl-3-((cyclopentyl-2-pentyl)-3-propxycarbonyl)]-1-methyl-ethylene]; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-2-(1-hexyl-6-oxymethyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=310 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-2-(1-ethyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=310 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxy-phenoxy]-dec-2-ene-oxycarbonyl]-1-methyl-ethylene]; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-2-(1-octyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=324 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-2-(1-octyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=310 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-2-(1-hexyl)-octoxycarbonyl]-1-methyl-ethylene]; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-3-(1-octyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=309 nm poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-2-(1-butyl)-octoxycarbonyl]-1-methyl-ethylene]; λ.sub.max. (in CH.sub.2Cl.sub.2)=299 nm poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxy]-2-(1-hexyl)hexoxycarbonyl]-1-methyl-ethylene] poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2-methoxyphenoxyl-2-(1-butyl)-octoxycarbonyl]-1-methyl-ethylene]; T.sub.g=28.5° C.;

EXAMPLE 2

Poly [1-[9-[4-[2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-nonyloxycarbonyl]-1-methyl-ethylene]

(12) ##STR00018##

(13) 2.5 g (5 mmol) of 2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenyl 4-[9-(2-methyl-acryloyloxy)-nonyloxy]-benzoate and 8.2 mg (0.05 mmol) of 2,2′-azo-bis-isobutyronitrile are dissolved in 10 ml of tetrahydrofuran (THF). The solution is flushed with a weak stream of argon for 30 minutes. Subsequently, the reaction vessel is sealed air-tight and heated to 55° C. After 24 hours the vessel is opened, the solution is diluted with 8 ml of THF and is added drop wise to 1.6 l of ethanol at room temperature while stirring vigorously. The separated polymer is filtered off and dried at 50° C. in a water-jet vacuum. For further purification, the polymer is dissolved in about 25 ml of dichloromethane and again precipitated in 1.75 l of methanol. This procedure is repeated until monomer is no longer detectable by thin-layer chromatography. Filtration and drying at 50° C. in a water-jet vacuum gave 2.1 g of poly [1-[9-[4-[2-methoxy-4-[(E)-2-methoxy-carbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-nonyloxycarbonyl]-1-methyl-ethylene]

(14) The 2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenyl 4-[9-(2-methyl-acryloyloxy)-nonyloxy]-benzoate used as the starting material was prepared according to the following procedure:

4-(9-Hydroxy-nonyloxy)-benzoic Acid

(15) 229.2 g (1.66 mol) of p-hydroxy-benzoic acid are dissolved in 600 ml of methanol and treated at 0° C. within 10 minutes with a solution of 151 g (3.77 mol) of NaOH in 480 ml of H.sub.2O. 271.2 g (1.99 mol) of 9-chloro-nonanol are slowly added dropwise to this solution. Finally, 0.75 g of potassium iodide is added and the batch is boiled under reflux for 60 hours. For the working up, the yellow solution is poured into 3 l of H.sub.2O and treated with 10% HCl (about 600 ml) until a pH value of 1 has been achieved. The milky suspension is filtered over a large suction filter. The residue is sucked dry and recrystallized twice from about 1.5 l of ethanol. This gives 230.6 g of 4-(9-hydroxy-nonyloxy)-benzoic acid as a fine white powder.

4-[9-(2-Methyl-acryloyloxy)-nonyloxy]-benzoic Acid

(16) 88 g (0.3 mol) of 4-(9-hydroxy-nonyloxy)-benzoic acid and 101.5 g (1.18 mol) of methacrylic acid are dissolved in 950 ml of chloroform. After the addition of 7.2 g (0.07 mol) of hydroquinone and 7.2 g (0.04 mol) of p-toluenesulphonic acid the batch is boiled under reflux on a water separator for 48 hours. The clear brown solution is subsequently evaporated, the residue is taken up in 1.5 l of diethyl ether, filtered and shaken five time with 300 ml of H.sub.2O each time. The organic phase is dried over Na.sub.2SO.sub.4, evaporated and the residue is recrystallized twice from methanol. After drying at 40° C. in a water-jet vacuum 48.2 g of 4-[9-(2-methyl-acryloyloxy)-nonyloxy]-benzoic acid remained behind as a white powder.

Methyl 4-hydroxy-3-methoxy-cinnamate

(17) ##STR00019##

(18) The preparation is effected analogously to Example 1 from 25 g (0.129 mol) of 4-hydroxy-3-methoxy-cinnamic acid and 180 ml of methanol with concentrated sulphuric acid as the catalyst. For purification, it is chromatographed on silica gel with dichloromethane/diethyl ether (19:1). This gives 21.78 g of methyl 4-hydroxy-3-methoxy-cinnamate as a pale yellow oil.

4-[(1E)-3-methoxy-3-oxoprop-1-enyl]-2-methylphenyl 4-{[9-(methacryloyloxy)nonyl]oxy}benzoate

(19) ##STR00020##

(20) 8.5 g (0.028 mol) of 4-[9-(2-methyl-acryloyloxy)-nonyloxy]-benzoate are treated with 6 ml of thionyl chloride and 3 drops of DMF and the mixture is heated to 90° C. for 2 hours. The excess thionyl chloride is completely removed firstly in a water-jet vacuum and subsequently in a high vacuum. The residual acid chloride is taken up in 20 ml of dichloromethane and is slowly added dropwise at 0° C. to a solution of 5.25 g (0.025 mol) of methyl 4-hydroxy-3-methoxy-cinnamate and 4.25 ml of triethylamine in 25 ml of THF. The batch is stirred at room temperature overnight, filtered and the filtrate is evaporated to dryness. The residue is purified by column chromatography on silica gel with dichloromethane/diethyl ether (19:1) and subsequently by recrystallization from ethanol/THF. 6.31 g of 2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenyl 4-[9-(2-methyl-acryloyloxy)-nonyloxy]-benzoate are isolated as a white powder.

(21) The following polymers are synthesized in an analogous manner: Poly [1-[10-[4-[2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-decyloxycarbonyl]-1-methyl-ethylene]; Poly [1-[11-[4-[2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-undecyloxycarbonyl]-1-methyl-ethylene].

APPLICATION EXAMPLES

(22) In the examples below, solutions of polymer materials according to the invention are prepared and are used for coating thin layers of the polymer material on a substrate.

(23) The polymer-layers are then photo-aligned by exposure to linearly polarized uv-light to generate an orientation layer. On top of each photo-aligned polymer-layer a layer of cross-linkable liquid crystals was prepared, which after having been oriented by the orientation layer are uv cross-linked. The cross-linked liquid crystal (LCP-) layer is analyzed by determination of the contrast ratio, which is a measure of the alignment quality.

(24) The procedure for the preparation of solutions of the polymer material, orientation layers, LCP-layers and the measurement of contrast ratio as well as the characterization of the LCP-layer is described below.

(25) Preparation of a Solution of the Polymer Material (=Composition)

(26) A solution of a polymer material is prepared by dissolving 2% by weight of the polymer material in cyclopentanone. The polymer solution is stirred for 30 minutes at room temperature.

(27) Preparation of an Orientation Layer

(28) A glass substrate is spin coated with the polymer solution at a spinning speed of 3000 rpm for 1 minute. The coated substrate is then dried at 180° C. for 10 minutes. The thickness of the resulting polymer-layer is about 50 nm.

(29) The polymer-layers are exposed to linearly polarized uv-light (LPUV) in the wavelength range of 280 to 340 nm. The substrate area is segmented into 8 stripes, each of which is irradiated with a different LPUV energy, namely 1, 2, 4, 8, 16, 32 and 64 up to 600 mJ/cm.sup.2, in order to study the energy dependence of the orientation performance. The polarization direction is the same for all segments.

(30) Preparation of LCP-Solutions

(31) LCP-solution S1:

(32) Mixture M1.sub.LCP, comprising cross-linkable liquid crystals consisted of:

(33) 67.4% LC1

(34) 19.2% LC2

(35) 9.6% C1

(36) 1.9% Irgacure® 369

(37) 1.9% BHT, 4-methyl-2, di-tertiary butyl phenol

(38) LCP-solution S1 is prepared by dissolving 15% by weight of mixture M1.sub.LCP in anisole and then stirring the solution for 30 minutes at 50° C.

(39) LCP-Solution S2:

(40) Mixture M2.sub.LCP, comprising cross-linkable liquid crystals consisted of:

(41) 77.0% LC1

(42) 14.4% LC3

(43) 4.8% LC4

(44) 1.9% Irgacure® 369

(45) 1.9% BT, 4-methyl-2, di-tertiary butyl phenol

(46) LCP-solution S2 is prepared by dissolving 10% by weight of mixture M2.sub.LCP in Anisole and then stirring the solution for 30 minutes at 50° C.

(47) ##STR00021##

(48) Preparation of a LCP Layer Aligned by the Orientation Layer

(49) An LCP layer is prepared on top of the orientation layer by spin-coating the respective LCP-solution at 1000 rpm for 2 minutes. The liquid crystal layer is then annealed for 10 minutes at 50° C. and subsequently the liquid crystals are cross-linked at room temperature in nitrogen atmosphere by irradiation with UV-A light of 2 mW/cm.sup.2 for 5 minutes.

(50) Measurement of Contrast Ratio

(51) Contrast ratio is measured with a polarizing microscope, equipped with a photo-multiplier as a light sensor. Measurements are done with the polarizers in crossed position. The substrate with the birefringent LCP-layer is fixed on a rotatable sample holder. For determination of the contrast ratio two measurements are performed. For the first measurement the sample is rotated to the position with the lowest intensity measured by the photo-multiplier. In this position the optical axis is parallel to one of the polarizers and the measured intensity is defined as the dark state intensity. Then the sample is rotated by 45°, which means that the optical axis is at 45° to both polarizers. The light intensity measured in this position is defined as the bright state intensity. The contrast of the birefringent LCP-layer is then determined by the ratio of intensities of bright state to dark state. The contrast ratio measured in this way is a measure for the alignment quality of the LCP-layer. If the liquid crystal layer is not oriented at all, then dark and bright state intensities are identical and the contrast ratio is 1:1.

(52) Evaluation of Orientation Thresholds

(53) For an efficient manufacturing process it is of interest: a) how much exposure energy does a photo-alignment layer require to achieve a certain contrast ratio in a LCP layer aligned by the orientation layer. Accordingly, a parameter Ecr500 is introduced, which is defined as the lowest exposure energy for the polymer, for which the contrast ratio in the LCP layer is 500:1. For the evaluation of Ecr500 the contrast ratio is determined in each of the stripes, which are photo-aligned with different energies, and then Ecr500 is evaluated by interpolation of the contrast ratio data.

(54) b) On the other hand, if the tact times and the polarized uv-light intensity in a production line are already fixed, the exposure energy for the polymer is also fixed. In that case the question arises what kind of contrast can be achieved in an LCP layer oriented by an orientation layer exposed to said exposure energy. Therefore, a second parameter CR4 is introduced for the evaluation in the examples, which is defined as the contrast ratio achieved in a LCP-layer, which is aligned by the orientation layer, wherein the orientation layer has been exposed to linearly polarized uv-light of 4 mJ/cm.sup.2.

EXAMPLE 1

(55) For each polymer material listed below, solution S1 was used to prepare LCP-layers, which are aligned by the orientation layer, according to the procedure described above, which means: preparation of a solution of the polymer material, preparation of an orientation layer, preparation of LCP solution S1 and finally the preparation of the LCP-layer, which is aligned by the orientation layer.

(56) The evaluation of the orientation performance parameters is then performed as described above.

(57) TABLE-US-00001 Ecr500 [mJ/cm.sup.2] CR4 poly [1-[3-[4-[(E)-2-methoxycarbonyl-vinyl]- 4.5 470:1 phenoxy]-propoxycarbonyl]-1-methyl-ethylene] poly [1-[4-[4-[(E)-2-methoxycarbonyl-vinyl]- 1.8 850:1 phenoxy]-butoxycarbonyl]-1-methyl-ethylene] poly [1-[5-[4-[(E)-2-methoxycarbonyl-vinyl]- 2.1 824:1 phenoxy]-pentoxycarbonyl]-1-methyl-ethylene] poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]- 1.9 1000:1  phenoxy]-hexoxycarbonyl]-1-methyl-ethylene] poly [1-[7-[4-[(E)-2-methoxycarbonyl-vinyl]- 465:1 phenoxy]-heptoxycarbonyl]-1-methyl-ethylene] poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]- 1.8 400:1 phenoxy]-octoxycarbonyl]-1-methyl-ethylene] poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]- 3 626:1 phenyl carbonyloxy]-hexoxycarbonyl]- 1-methyl-ethylene] poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]- 1.8 910:1 phenyl carbonyloxy]-octoxycarbonyl]-1-methyl- ethylene] poly [1-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-2- 5.6 402:1 methoxyphenoxy]-hexoxycarbonyl]-1-methyl- ethylene]; poly [1-[8-[4-[(E)-2-methoxycarbonyl-vinyl]-2- 4.3 474:1 methoxyphenoxy]-octoxycarbonyl]-1-methyl- ethylene]

EXAMPLE 2

(58) For each polymer material listed below, solution S2 was used to prepare aligned LCP-layers, which are aligned by the orientation layer, according to the procedure described above, which means: preparation of solution of polymer material, preparation of a photo-alignment layer, preparation of LCP solution S2 and finally the preparation of the aligned LCP layer, which is aligned by the orientation layer.

(59) The evaluation of the orientation performance parameters was then performed as described above.

(60) TABLE-US-00002 Ecr500 [mJ/cm.sup.2] CR4 poly [1-[10-[4-[2-methoxy-4-[(E)-2- 8  60:1 methoxycarbonyl-vinyl]-phenoxycarbonyl]- phenoxy]-decyloxycarbonyl]-1-methyl- ethylene] poly [1-[11-[4-[2-methoxy-4-[(E)-2- 4 500:1 methoxycarbonyl-vinyl]-phenoxycarbonyl]- phenoxy]-undecyloxycarbonyl]-1-methyl- ethylene]