Photoalignment composition for the stabilization of the pre-tilt angle in liquid crystal layers

Abstract

The present invention relates to a photoalignment composition for the alignment of liquid crystals and the stabilization of the pre-tilt angle in liquid crystal layers. Further the present invention relates to the liquid crystal alignment film and coating layer prepared from the said composition and the use to fabricate optical and electrooptical elements and devices.

Claims

1. A liquid crystal photoalignment composition comprising: a photoaligning material that is not a polyimide and/or polyamic acid compound, comprising a photoalignment group selected from the group consisting of: cinnamate group, stilbene group, cyanostilbene group, coumarine group, quinolone group, azo group, chalcone group, mono- and di- acetylene groups; benzylidenephthalimidine group, benzylideneacetophene group, phenylenediacryloyl group; chromone group; chromene group and stilbazole group; wherein said photoalignment group can be substituted or unsubstituted; and a polyimide and/or polyamic acid compound, each comprising repeating structural units (Ia) and/or (Ib) and optionally comprising different repeating structural units (IIIa) and/or (IIIb); wherein the repeating structural units (Ia) and (Ib) are represented by formulae: ##STR00055## wherein Q is a tetravalent organic residue of a tetracarboxylic dianhydride which is selected from the group consisting of: 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride; 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride; 2,3,5-tricarboxycyclopentylacetic acid dianhydride; tetrahydro-4,8-methanofuro[3,4-d]oxepin-1,3,5,7-tetrone; 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride; hexahydrofuro[3′,4′:4,5]cyclopenta[1,2-c]pyran-1,3,4,6-tetrone; 5-(2,5-dioxotetrahydrofuran-3-yl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride; pyromellitic acid dianhydride; 4-(2,5-dioxotetrahydrofuran-3-yl)tetrahydronaphthalene-1,2-dicarboxylic acid dianhydride; 5-(2,5-dioxotetrahydro-3-furanyl)-5-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione; 5-(2,5-dioxotetrahydro-3-furanyl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione; 5-(2,5-dioxotetrahydro-3-furanyl)-7-methyl-3a,4,5,7a-tetrahydro-2-benzofuran-1,3-dione; 4-tert-butyl-6-(2,5-dioxotetrahydro-3-furanyl)-2-benzofuran-1,3-dione; 4,4′-(hexafluorneoisopropylidene)diphthalic acid dianhydride; bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride; and tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone; and wherein n is ≥1; and wherein A is a divalent organic residue of a H.sub.2N—A—NH.sub.2 diamine represented by a compound of formula (IVa), (IVb), (IVc), (VIII), (IX), (XII), (XIII), (XIV), (XV), (XVIIIa) or (XVIIIb): ##STR00056## ##STR00057## wherein X.sub.1, X.sup.1, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.10, X.sup.11, X.sup.13 and X.sup.14 are linking groups which are selected from a single bond, unsubstituted or mono- or poly-substituted C.sub.1-C.sub.8 alkylene; unsubstituted or mono- or poly-substituted phenyl, unsubstituted or mono- or poly-substituted naphthalene; unsubstituted or mono- or poly-substituted anthracene, or alkoxy groups; and wherein the substituent A of formulae (IVa), (IVb), (IVc), (VIII), (IX), (XII), (XIII) and (XIV) is selected from NH, CH.sub.2, O or S; and wherein repeating structural units (IIIa) and (IIIb) are represented by formulae: ##STR00058## wherein m is greater than 0; and wherein Q has the same meaning as defined above; and wherein Q in the repeating structural units of formula (IIIa) or (IIIb) is the same or different than in the repeating structural units of formula (Ia) or (Ib); and wherein B is a divalent diamine residue.

2. The liquid crystal photoalignment composition according to claim 1, wherein X.sub.1, X.sup.1, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.10, X.sup.11, x.sup.13 and X.sup.14 are selected from a single bond or a straight-chain or branched, substituted or unsubstituted C.sub.1-C.sub.8 alkylene group, wherein one or more C-atom(s) may be substituted by a “bridging group” which is represented by a single bond, phenylene, cyclohexylene or —O—, and wherein the substituent A of formulae (IVa), (IVb), (IVc), (VIII, (IX), (XII), (XIII) and (XIV) is selected from NH, CH.sub.2, O or S.

3. The liquid crystal photoalignment composition according to claim 1, wherein the H.sub.2N—A—NH.sub.2 diamine for the divalent organic residue for A in formulae (Ia) and (Ib) is selected from the following compounds: ##STR00059##

4. The liquid crystal photoalignment composition according to claim 1, wherein the H.sub.2N—A—NH.sub.2 diamine is at least one of compounds of formulae (XIX), (XXI), (XXII), (XXIII), (XXIV), (XXV), and (XXVI): ##STR00060##

5. The liquid crystal photoalignment composition according to claim 1, wherein the polyimide and/or polyamic acid compound each further comprise repeating structural units according to formulae (IIIa) or (IIIb).

6. The liquid crystal photoalignment composition according to claim 1, wherein the photoaligning material is a homopolymer or a copolymer.

7. The liquid crystal photoalignment composition according to claim 1, wherein the photoalignment group is selected from the group consisting of cinnamate group, cyanostilbene group, azo group and coumarine group.

8. The liquid crystal photoalignment composition according to claim 1, wherein the.

9. The liquid crystal photoalignment composition according to claim 1, wherein the unsubstituted, or mono- or poly-substituted C.sub.1-C.sub.8 alkylene group for X.sub.1, X.sup.1, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.10, X.sup.11, X.sup.13 and X.sup.14 is methylene, ethylene, propylene, butylene or pentylene.

10. The liquid crystal photoalignment composition according to claim 1, further comprising a solvent or solvent mixture and optionally at least one additive.

11. A method of using the liquid crystal photoalignment composition according to claim 1, comprising: orienting and stabilizing the pre-tilt angle of vertically aligned liquid crystals with the liquid crystal photoalignment composition.

12. A liquid crystal orientation layer comprising the liquid crystal photoalignment composition according to claim 1.

13. Structured or unstructured optical and electro-optical elements and devices comprising the liquid crystal orientation layer according to claim 12.

Description

EXAMPLES

Definitions

(1) NMP=N-methyl-pyrrolidone

(2) Following examples will illustrate in a non-limiting way the invention. If not stated otherwise, the chemical names of the used compounds are following the IUPAC rules. UV/Vis spectra have been measured with Hitachi U2910 spectrometer in solution of NMP at room temperature.

Synthetic Example 1

1.1 Preparation of 4-(4,4,4-trifluorobutoxy)benzoic acid

(3) ##STR00039##

(4) 55.00 g (0.408 mol) 4,4,4-trifluorobutan-1-ol are dissolved in 550 mL tetrahydrofuran, 142 mL (0.102 mol) triethylamine are added at room temperature. 38 mL (0.490 mol) methanesulfonyl chloride were added dropwise under nitrogen. The mixture is stirred for 1 h at 0-5° C. The beige suspension is Hyflo-filtrated and washed with tetrahydrofuran. The filtrate is concentrated. The residue is dissolved in 1.4 L NMP 62.70 g (0.408 mol) of methyl 4-hydroxybenzoate and 226.00 g (1.43 mol) of potassium carbonate are added to the lightly brown solution. The reaction suspension is allowed to react at 80° C. for 14 h. 1 L (1.0 mol) of a 1N NaOH solution is added to the above mixture. The suspension is heated at reflux temperature for 30 min until the reaction is completed. The reaction mixture is allowed to cool at room temperature and thrown in cold water. The solution is carefully acidified with a 25% HCl solution and is stirred for 15 min. The product is filtrated off, washed with water and dried overnight at room temperature under vacuum to give 99.00 g of 4-(4,4,4-trifluorobutoxy)benzoic acid as a white solid.

1.2 Preparation of 4-formylphenyl 4-(4,4,4-trifluorobutoxy)benzoate

(5) ##STR00040##

(6) 6.89 g (56.4 mmol) of 4-hydroxybenzaldehyde, 14.0 g (56.4 mmol) of 4-(4,4,4-trifluorobutoxy)benzoic acid, 0.69 g (5.6 mmol) of 4-dimethylaminopyridine are dissolved in 100 mL of dichloromethane. 11.89 g (62.0 mmol) of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC hydrochloride) are added at 0° C. The solution is stirred for 1 h at 0° C. and allowed to stir at room temperature overnight. After 22 hours at room temperature the reaction mixture was partitioned between dichloromethane and water; the organic phase is washed repeatedly with water, dried over sodium sulphate, filtered and concentrated by rotary evaporation. Crystallization form 2-propanol at 0° C. give 17.1 g of 4-formylphenyl 4-(4,4,4-trifluorobutoxy)benzoate as colourless crystals.

1.3 Preparation of (E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoic acid

(7) ##STR00041##

(8) 5.00 g (14.2 mmol) of 4-formylphenyl 4-(4,4,4-trifluorobutoxy)benzoate and 3.00 g (28.4 mmol) of malonic acid are dissolved in 18 mL (227.1 mmol) of pyridine. 1.21 g (14.2 mmol) of piperidine are added to the suspension which is allowed to react at 100° C. under argon for 1.5 h. The yellow solution is then thrown on ice. The solution is carefully acidified to pH=1-2 with a 25% HCl solution and is stirred for 15 min. The product is filtrated off and dried at room temperature under vacuum for 10 h to give 5.2 g of (E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoic acid as white powder.

1.4 Preparation of 2-(2,4-dinitrophenyl)ethanol

(9) ##STR00042##

(10) 22.6 g (100 mmol) 2,4-dinitrophenylacetic acid are dissolved in 150 mL tetrahydrofuran and added dropwise in a the course of 2 hours to 300 mL (300 mmol) of a borane-tetrahydrofuran complex 1.0 M solution in tetrahydrofuran. After 3 hours at 25° C., 200 mL water are carefully added. The reaction mixture is then partitioned between ethyl acetate and water; the organic phase was washed repeatedly with water, dried over sodium sulfate, filtered and concentrated by rotary evaporation. Chromatography of the residue on 400 g silica gel using toluene:ethyl acetate 1:1 as eluent and crystallization form ethylacetate:hexane mixture to yield 20.7 g of 2-(2,4-dinitrophenyl)ethanol as yellowish crystals.

1.5 [4-[(E)-3-[2-(2,4-dinitrophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl]4-(4,4,4-trifluorobutoxy)benzoate

(11) ##STR00043##

(12) 2.50 g (11.8 mmol) of 2-(2,4-dinitrophenyl)ethanol, 4.65 g (11.8 mmol) of (E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoic acid, 144 mg (1.2 mmol) of 4-dimethylaminopyridine are dissolved in 30 mL of dichloromethane. 2.48 g (13.0 mmol) of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC hydrochloride) are added at 0° C. The solution is stirred for 1 h at 0° C. and allowed to stir at room temperature overnight. After 22 hours at room temperature the reaction mixture is partitioned between dichloromethane and water. The organic phase is washed repeatedly with water, dried over sodium sulphate, filtered and concentrated by rotary evaporation. Chromatography of the residue on 200 g silica gel using toluene:ethyl acetate 95:5 as eluent and crystallization form ethylacetate:hexane mixture to yield 5.33 g [4-[(E)-3-[2-(2,4-dinitrophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate as slightly yellowish crystals.

1.6 Preparation of [4-[(E)-3-[2-(2,4-diaminophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate

(13) ##STR00044##

(14) 5.04 g (8.57 mmol) of [4-[(E)-3-[2-(2,4-dinitrophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate are dissolved in a mixture of 54 mL of N,N-dimethylformamide and 6 mL water. 13.9 g (51.4 mmol) ferric chloride hexahydrate are added. 5.60 g (85.7 mmol) Zinc powder are added portionwise within 60 min. The mixture is allowed to react for 2 hours. The reaction mixture is then partitioned between ethyl acetate and water and filtered. The organic phase is washed repeatedly with water, dried over sodium sulfate, filtered and concentrated by rotary evaporation. Filtration of the residue on 200 g silica gel using toluene:ethyl acetate (1:3) as eluent and crystallization form ethylacetate:hexane mixture yielded 3.21 g [4-[(E)-3-[2-(2,4-diaminophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate as yellowish crystals. MS: 528.1 [M.sup.+]

(15) .sup.1H-NMR (CDCl.sub.3, 400 MHz): 2.10 (m, 2H), 2.34 (m, 2H), 2.82 (t, 2H), 3.50 (s, 2H), 3.88 (s, 2H), 4.12 (t, 2H), 4.33 (t, 2H), 6.09 (m, 2H), 6.43 (d, 1H), 6.86 (d, 1H), 6.97 (m, 2H), 7.24 (m, 2H), 7.59 (m, 2H), 7.70 (d, 1H), 8.12 ppm (m, 2H).

Synthetic Example 2

2.1 Preparation of 2-(2-carboxy-4-nitro-phenyl)-5-nitro-benzoic acid

(16) ##STR00045##

(17) 30.0 g (120.13 mmol) 2-(2-carboxyphenyl)benzoic acid are dissolved at room temperature in 469 g (4.59 mol) concentrated sulfuric acid (96%). The solution is cooled to −15° C. and a mixture of 92.4 g (1.011 mol) concentrated nitric acid (69%) and 12.0 g (0.117 mol) concentrated sulfuric acid (96%) is added slowly so that the mixture temperature is maintained below 0° C. After the addition the solution is allowed to react at room temperature for 24 h. After the mixture is poured onto crushed ice, the precipitate that formed is collected by filtration, washed with water and dried at room temperature under vacuum for 10 h.

2.2 Preparation of [2-[2-(hydroxymethyl)-4-nitro-phenyl]-5-nitro-phenyl]methanol

(18) ##STR00046##

(19) 3.6 g (10.83 mmol) 2-(2-carboxy-4-nitro-phenyl)-5-nitro-benzoic acid are dissolved in 25 mL tetrahydrofuran and added dropwise in a course of 1 hour to 65 mL (65.02 mmol) of a borane-tetrahydrofuran complex 1.0 M solution in tetrahydrofuran. After 19 hours at 25° C., 50 mL water are carefully added. After 1 h the solution is acidified to pH=1-2 with 10 mL 1N HCl solution and allowed to stirred for 30 min. The reaction mixture is then partitioned between ethyl acetate and water; the organic phase is washed repeatedly with water, dried over sodium sulfate, filtered and concentrated by rotary evaporation. The residue, 4.2 g of [2-[2-(hydroxymethyl)-4-nitro-phenyl]-5-nitro-phenyl]methanol as white powder is used without further purification.

2.3 Preparation of [4-[(E)-3-[[5-nitro-2-[4-nitro-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate

(20) ##STR00047##

(21) 3.92 g (12.8 mmol) of [2-[2-(hydroxymethyl)-4-nitro-phenyl]-5-nitro-phenyl]methanol, 13.20 g (33.5 mmol) of (E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoic acid, 0.630 mg (5.15 mmol) of 4-dimethylaminopyridine are dissolved in 200 mL of dichloromethane. 6.91 g (11.16 mmol) of N,N′-dicyclohexylcarbodiimide are added at 0° C. The solution is stirred for 2 h at 0° C. and allowed to stir at room temperature overnight. After 22 hours at room temperature the reaction mixture is partitioned between dichloromethane and water. The organic phase is washed repeatedly with water, dried over sodium sulphate, filtered and concentrated by rotary evaporation. Chromatography of the residue on 150 g silica gel using toluene:ethyl acetate 9:1 as eluent to yield 12.0 g of [4-[(E)-3-[[5-nitro-2-[4-nitro-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate as white crystals.

2.4 Preparation of [4-[(E)-3-[[5-amino-2-[4-amino-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate

(22) ##STR00048##

(23) 2.27 g (2.14 mol) of [4-[(E)-3-[[5-nitro-2-[4-nitro-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate are dissolved in a mixture of 40 mL of N,N-dimethylformamide and 3 mL water. 3.48 g (12.8 mmol) ferric chloride hexahydrate are added. 1.40 g (21.4 mmol) Zinc powder are added portionwise within 40 min. The mixture is allowed to react for 2 hours. The reaction mixture is then partitioned between ethyl acetate and water and filtered. The organic phase is washed repeatedly with water, dried over sodium sulfate, filtered and concentrated by rotary evaporation.

(24) Chromatography of the residue on 100 g silica gel using toluene:ethyl acetate 7:3 as eluent yield 1.74 g [4-[(E)-3-[[5-amino-2-[4-amino-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate as yellowish crystals. MS: 997.4 [M+H].sup.+, 1014.4 [M+NH.sub.4].sup.+

(25) .sup.1H-NMR (DMSO-d.sub.6, 400 MHz): 1.98 (m, 4H), 2.44 (m, 4H), 4.15 (t, 4H), 4.86 (s, 4H), 5.13 (s, 4H), 6.56 (m, 4H), 6.71 (m, 2H), 6.83 (d, 2H), 7.10 (d, 4H), 7.28 (d, 4H), 7.61 (d, 2H), 7.76 (d, 4H), 8.10 ppm (d, 4H).

Synthetic Example 3

3.1 Preparation of N-(2-aminophenyl)-3,5-dinitro-benzamide

(26) ##STR00049##

(27) At −78° C., 5 g (21.69 mmol) of 3,5-dinitrobenzoyl chloride dissolved in 80 mL dry THF is added dropwise to 4.69 g (43.37 mmol) benzene-1,2-diamine dissolved in 175 mL dry THF. After 4 h the reaction mixture was allowed to reach RT and ca. 800 mL deionised water was added to precipitate the product. The precipitate was filtered off and rinsed with 100 mL deionized water. The crude product is purified by heating to reflux in 400 mL ethyl acetate and 1300 mL acetonitrile and subsequent hot filtration. The solution is cooled to 0° C., the forming precipitate filtered, washed with 100 mL ethyl acetate and dried in the oven at 40° C. to give 3.77 g (57% yield) of N-(2-aminophenyl)-3,5-dinitro-benzamide as orange solid.

(28) .sup.1H-NMR (DMSO-d.sub.6, 300 MHz): 5.09 (s, 2H), 6.44-6.69 (m, 1H), 6.79 (dd, 1H), 6.99-7.05 (m, 1H), 7.15 (dd, 1H), 9.00 (t, 1H), 9.19 (d, 2H), 10.29 ppm (s, 1H).

3.2 Preparation of 2-(3,5-dinitrophenyl)-1H-benzimidazole

(29) ##STR00050##

(30) To 5.6 g (18.53 mmol) N-(2-aminophenyl)-3,5-dinitro-benzamide in a 3-neck flask equipped with condenser and NaOH-outlet 47.5 mL (37.06 mmol, 0.8 M) of Eaton's reagent (7% w/w P.sub.2O.sub.5 in MeSO.sub.3H) is added and heated for 3 h at 130° C. The reaction mixture reached RT and is added carefully dropwise to 1.2 L of a 7% NaCO.sub.3 solution. The precipitate is filtered and washed with 500 mL deionized water, dried in the oven at 40° C. to give 5.18 g, from which 4.6 g are reheated in 180 mL DMF, cooled to RT and 7 mL water are added. The precipitate is filtered and dried in the oven at 40° C. to give 2.36 g (44.8% yield) of 2-(3,5-dinitrophenyl)-1H-benzimidazole as yellow solid.

(31) .sup.1H-NMR (DMF-d.sub.7, 300 MHz): 7.31-7.38 (m, 2H), 7.73-7.79 (m, 2H), 8.97 (t, 1H), 9.47 (d, 2H), 13.67 ppm (s, 1H).

3.3 Preparation of 5-(1H-benzimidazol-2-yl)benzene-1,3-diamine

(32) ##STR00051##

(33) 2.5 g (8.79 mmol) 2-(3,5-dinitrophenyl)-1H-benzimidazole is dissolved in 100 mL DMF and hydrogenated by 0.1 w % Pt/C and 4 bar H.sub.2 at 80° C. After 1.5 h the hot reaction mixture is rinsed over a Hyflo pad and 400 mL isopropyl ether is added. The red lower phase is separated and evaporated to dryness and dried in the oven at 40° C. The solid is recrystallized with 2-propanol/toluene and 2-propanol/n heptane to give 760 mg (38.6% yield) of 5-(1H-benzimidazol-2-yl)benzene-1,3-diamine as yellowish solid.

(34) .sup.1H-NMR (DMSO-d.sub.6, 300 MHz): 4.93 (s, 4H), 5.96 (t, 1H), 6.61 (d, 2H), 7.11-7.23 (m, 2H), 7.51 (s, 2H), 12.51 (s, 1H).

Synthetic Example 4

4.1 Preparation of N-(cyano-4-nitrophenyl)-4-nitrobenzamide

(35) ##STR00052##

(36) 28.5 g (0.154 mol) of 4-nitrobenzoylchoride is added under stirring to 25 g (0.153 mol) of 2-amino-5-nitrobenzonitrile suspended in 100 mL pyridine and additional 100 mL pyridine are added. The reaction mixture is heated for 4 h and slowly allowed to reach room temperature and poured into 1.5 L 2% HCL solution. The orange solid is filtered and washed well with deionized water. 67.7 g of wet crude product is reheated in 750 mL acetone, hot filtered, and 750 mL deionized water is added, stirred for 10 minutes and precipitate is filtered and dried in the oven at 40° C. to give 43.44 g (91% yield) of N-(cyano-4-nitrophenyl)-4-nitrobenzamide.

(37) .sup.1H-NMR (DMSO-d.sub.6, 300 MHz): 7.92 (d, 1H), 8.22-8.27 (m, 2H), 8.42-8.46 (m, 2H), 8.58 (dd, 1H), 8.81 (d, 1H), 11.36 ppm (s, 1H).

4.2 Preparation of 6-nitro-2-(4-nitrophenyl)-3H-quinazolin-4-one

(38) ##STR00053##

(39) 320 mL of 16% NaOH solution and 91.2 mL 30% hydrogen peroxide dissolved in 400 mL ion-free water is added to 20 g (0.064 mol) N-(cyano-4-nitrophenyl)-4-nitrobenzamide. The orange suspension is heated for 1.5 h, slowly allowed to reach room temperature and is diluted with 600 mL water. The reaction mixture is poured into 1.2 L of 5% H.sub.2SO.sub.4, stirred for 15 minutes at room temperature, cooled to 0° C., stirred for 10 minutes. White precipitate is filtered and washed with 400 mL deionized water. 83 g of crude product is reheated in 500 mL DMF to 150° C., slowly reach room temperature, stirred for 10 minutes at 00. The precipitate is dried in the oven at 40° C. to give 15.48 g (77.4% yield) of 6-nitro-2-(4-nitrophenyl)-3H-quinazolin-4-one.

(40) .sup.1H-NMR (DMSO-d.sub.6, 300 MHz): 7.94 (dd, 1H), 8.36-8.44 (m, 4H), 8.57 (dd, 1H), 8.81-8.82 (m, 1H), 13.25 ppm (s, 1H).

4.3 Preparation of 6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one

(41) ##STR00054##

(42) 15.3 g (0.049 mol) 6-nitro-2-(4-nitrophenyl)-3H-quinazolin-4-one is dissolved in 500 mL DMF and hydrogenated by 0.1 w % Pt/C and 4 bar H.sub.2 at 80° C. After 1 h the hot reaction mixture is rinsed over Hyflo pad and 500 mL water is added. The precipitate is filtered and dried in the oven at 40° C. to give 7.9 g. 5.11 g are dissolved in 700 mL technical alcohol, and 300 mL water first precipitate is discarded, another 5 L deionized water are added and left standing overnight. Next day the precipitate is filtered, dried in the oven at 40° C. to give 750 mg of 6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one as yellowish solid.

(43) .sup.1H-NMR (DMSO-d.sub.6, 300 MHz): 5.49 (s, 2H), 5.64 (s, 2H), 6.59-6.64 (m, 2H), 7.06 (dd, 1H), 7.19 (d, 1H), 7.37 (d, 1H), 7.86 (d, 2H), 11.69 ppm (s, 1H). LC-MS: 253.1 [M+H].sup.+.

Example 1

Preparation of Polyamic Acid Solution PAA1

(44) 2.000 g of 4,4′-diaminodiphenyl ether are dissolved in 15.79 g NMP under mechanical stirring. 0.046 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine are added. The mixture is cooled and further stirred. 1.799 g of 1,2,3,4-cyclobutantetracarboxylic acid dianhydride are added and stirred at room temperature. The resulting polyamic acid solution PAA1, which contains 2% of 2-(4-aminophenyl)-1H-benzimidazol-5-amine has an intrinsic viscosity at 30° C. of 0.40 dL/g.

(45) UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine incorporated into PAA1 at 341 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA1/g (NMP)).

Example 2

Preparation of Polyamic Acid Solution PAA2

(46) Analogue to example 1, PAA2 was prepared using 2.000 g of 4,4′-diaminodiphenyl ether, 16.14 of NMP, 0.093 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and 1.836 g of 1,2,3,4-cyclobutantetracarboxylic acid dianhydride. The obtained polyamic acid solution PAA2, which contain 4% of 2-(4-aminophenyl)-1H-benzimidazol-5-amine, has an intrinsic viscosity at 30° C. of 0.41 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine incorporated into PAA2 at 341 nm in NMP solution (with approximately double intensity compared to PAA1).

Example 3

Preparation of Polyamic Acid Solution PAA3

(47) Analogue to example 1, PAA3 was prepared using 2.000 g of 4,4′-diaminodiphenyl ether, 16.687 g of NMP, 0.169 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and 1.896 g of 1,2,3,4-cyclobutantetracarboxylic acid dianhydride. The obtained polyamic acid solution PAA3, which contains 7% of 2-(4-aminophenyl)-1H-benzimidazol-5-amine, has an intrinsic viscosity at 30° C. of 0.39 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine incorporated into PAA3 at 341 nm in NMP solution (with approximately 3.5 times intensity compared to PAA1).

Example 4

Preparation of Polyamic Acid Solution PAA4

(48) PAA4 was prepared using 2.000 g of 2,2′-dimethylbenzidine, 16.86 g of NMP, 0.088 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and 2.068 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA4, which contains 4% of 2-(4-aminophenyl)-1H-benzimidazol-5-amine, has an intrinsic viscosity at 30° C. of 0.53 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine incorporated into PAA4 at 338 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA4/g (NMP)).

Example 5

Preparation of Polyamic Acid Solution PAA5

(49) Analogue to example 4, PAA5 was prepared using 2 g of 2,2′-dimethylbenzidine, 17.4 g of NMP, 0.162 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and 2.14 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA5, which contains 7% of 2-(4-aminophenyl)-1H-benzimidazol-5-amine, has an intrinsic viscosity at 30° C. of 0.52 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine incorporated into PAA5 at 338 nm in NMP solution (with approximately 1.75 times intensity compared to PAA4).

Example 6

Preparation of Polyamic Acid Solution PAA6

(50) Analogue to example 4, PAA6 was prepared using 1 g of 2,2′-dimethylbenzidine, 8.4 g of NMP, 0.038 g of 2-(4-amino-2-pyridyl)pyridine-4-amine and 1.03 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA6, which contains 4% of 2-(4-amino-2-pyridyl)pyridine-4-amine, has an intrinsic viscosity at 30° C. of 0.85 dL/g.

Example 7

Preparation of Polyamic Acid Solution PAA7

(51) Analogue to example 4, PAA7 was prepared using 2 g of 2,2′-dimethylbenzidine, 16.9 g of NMP, 0.045 g of (2-(4-aminophenyl)-1,3-benzoxazol-6-amine, 0.044 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and 2.09 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA7, which contains 2% of 2-(4-aminophenyl)-1,3-benzoxazol-6-amine and 2% 2-(4-aminophenyl)-1H-benzimidazol-5-amine, has an intrinsic viscosity at 30° C. of 0.58 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and (2-(4-aminophenyl)-1,3-benzoxazol-6-amine incorporated into PAA7 at 342 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA7/g (NMP)).

Example 8

Preparation of Polyamic Acid PAA8

(52) Analogue to example 4, PAA8 was prepared using 2 g of 2,2′-dimethylbenzidine, 16.9 g of NMP, 0.088 g of (2-(4-aminophenyl)-1,3-benzoxazol-6-amine and 2.09 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA8, which contains 4% of 2-(4-aminophenyl)-1,3-benzoxazol-6-amine, has an intrinsic viscosity at 30° C. of 0.57 dL/g. UV/Vis spectroscopy showed characteristic band of (2-(4-aminophenyl)-1,3-benzoxazol-6-amine incorporated into PAA8 at 347 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA8/g (NMP)).

Example 9

Preparation of Polyamic Acid PAA9

(53) 0.1 g of 6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one, synthesized as described in synthetic example 4, are suspended in 0.74 g NMP 81.9 mg tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone are added under mechanical stirring at room temperature. The resulting polyamic acid solution PAA9, which contains 100% (6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one has an intrinsic viscosity at 30° C. of 0.41 dL/g. UV/Vis spectroscopy showed characteristic band of (6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one at λ.sub.max 336 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA9/g (NMP)).

Example 10

Preparation of Polyamic Acid PAA10

(54) Analogue to example 4, PAA10 was prepared using 1 g of 2,2′-dimethylbenzidine, 8.44 g of NMP, 0.050 g of (4-[5-(4-aminophenyl)-1,3,4-oxadiazol-2-yl]aniline and 1.03 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA10, which contains 4% of (4-[5-(4-aminophenyl)-1,3,4-oxadiazol-2-yl]aniline, has an intrinsic viscosity at 30° C. of 0.60 dL/g.

(55) UV/Vis spectroscopy showed characteristic band of (4-[5-(4-aminophenyl)-1,3,4-oxadiazol-2-yl]aniline) incorporated into PAA10 at 336 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA10/g (NMP)).

Example 11

Preparation of Polyamic Acid PAA11

(56) PAA11 was prepared using 2 g of 2-amino-4-[1-(3-amino-4-hydroxyphenyl)-1-methyl-ethyl]phenol, 15.44 g of NMP, 0.072 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and 1.77 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA11, which contains 4% of 2-(4-aminophenyl)-1H-benzimidazol-5-amine, has an intrinsic viscosity at 30° C. of 0.31 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine incorporated into PAA11 at 338 nm in NMP solution (with similar intensity compared to PAA4).

Example 12

Preparation of Polyamic Acid PAA12

(57) 0.5 g of 2-(4-aminophenyl)-1H-benzimidazol-5-amine are suspended in 4 g NMP and 0.5 g tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone are added under mechanical stirring at room temperature. The resulting polyamic acid solution PAA12, which contains 100% 2-(4-aminophenyl)-1H-benzimidazol-5-amine has an intrinsic viscosity at 30° C. of 0.44 dL/g. UV/Vis spectroscopy showed characteristic band of 2-(4-aminophenyl)-1H-benzimidazol-5-amine at λ.sub.max of 338 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA12/g (NMP)).

Example 13

Preparation of Polyamic Acid PAA13

(58) Analogue to example 4, PAA13 was prepared using 1 g of 2,2′-dimethylbenzidine, 8.45 g of NMP, 0.050 g of (6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one, as described in synthetic example 4 and 1.03 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA13, which contains 4% of (6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one, has an intrinsic viscosity at 30° C. of 0.38 dL/g. UV/Vis spectroscopy showed characteristic band of (6-amino-2-(4-aminophenyl)-3H-quinazolin-4-one at λ.sub.max 336 nm in NMP solution.

Example 14

Preparation of Polyamic Acid PAA14

(59) Analogue to example 4, PAA14 was prepared using 2 g of 2,2′-dimethylbenzidine, 16.83 g of NMP, 0.077 g of 9H-carbazole-3,6-diamine and 2.07 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA14, which contains 4% of 9H-carbazole-3,6-diamine, has an intrinsic viscosity at 30° C. of 0.42 dL/g. UV/Vis spectroscopy showed characteristic band of (9H-carbazole-3,6-diamine incorporated into PAA14 at 355 nm in NMP solution (at a concentration of 1.9×10.sup.−4 g PAA14/g (NMP)).

Example 15

Preparation of Polyamic Acid PAA15

(60) Analogue to example 1, PAA15 was prepared using 1 g of 2,2′-dimethylbenzidine, 8.44 g of NMP, 0.044 g of 5-(1H-benzimidazol-2-yl)benzene-1,3-diamine, synthesized as described in synthetic example 3, and 1.03 g of tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone. The obtained polyamic acid solution PAA15, which contains 4% of 5-(1H-benzimidazol-2-yl)benzene-1,3-diamine, has an intrinsic viscosity at 30° C. of 0.40 dL/g. UV/Vis spectroscopy showed characteristic band of 5-(1H-benzimidazol-2-yl)benzene-1,3-diamine incorporated into PAA15 at 309 and 324 nm in NMP solution (at a concentration of 9.8×10.sup.−6 g PAA15/g (NMP)).

Example 16

Comparative Polyamic Acid Solution PAAC1

(61) Comparative polyamic acid solution PAAC1 is analogue to PAA2 but without 2-(4-aminophenyl)-1H-benzimidazol-5-amine, prepared in a similar way, and has an intrinsic viscosity at 30° C. of 0.37 dL/g. UV/Vis spectroscopy showed no band at 341 nm (one band at λ.sub.max 268 nm).

Example 17

Comparative Polyamic Acid Solution PAAC2

(62) Comparative polyamic acid solution PAAC2 is analogue to PAA4 but without 2-(4-aminophenyl)-1H-benzimidazol-5-amine, prepared in a similar way, and has an intrinsic viscosity at 30° C. of 0.51 dL/g. UV/Vis spectroscopy showed no band at 338 nm (one band at λ.sub.max 266 nm).

Example 18

Photo Alignment Polymer Solution LPP1

(63) Photo alignment polymer solution LPP1 is prepared as a 30% solution of copolyamic acid based on 70 mol % of [4-[(E)-3-[2-(2,4-diaminophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate (synthesized as described in synthetic example 1), 30 mol % of [4-[(E)-3-[[5-amino-2-[4-amino-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate (synthesized as described in synthetic example 2) and tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone in NMP, and has an intrinsic viscosity at 30° C. of 0.35 dL/g.

Example 19

Photo Alignment Polymer Solution LPP2

(64) Photo alignment polymer solution LPP2 is prepared as a 30% solution of copolyamic acid based on 90 mol % of [4-[(E)-3-[2-(2,4-diaminophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate, 6.1 mol % of [4-[(E)-3-[[5-amino-2-[4-amino-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate, 3.9 mol % of 3-(3,5-diaminobenzoate) Cholestan-3-ol and tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone in NMP, and has an intrinsic viscosity at 30° C. of 0.26 dL/g.

Example 20

Photo Alignment Polymer Solution LPP3

(65) Photo alignment polymer solution LPP2 is prepared as a 30% solution of copolyamic acid based on 69 mol % of [4-[(E)-3-[2-(2,4-diaminophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate, 29 mol % of [4-[(E)-3-[[5-amino-2-[4-amino-2-[[(E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoyl]oxymethyl]phenyl]phenyl]methoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate, 2 mol % of 2-(4-aminophenyl)-1H-benzimidazol-5-amine and tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone in NMP, and has an intrinsic viscosity at 30° C. of 0.26 dL/g.

Example 21

Photo Alignment Polymer Solution LPP4

(66) Photo alignment polymer solution LPP4 is a 30% solution of polyamic acid based on [4-[(E)-3-[2-(2,4-diaminophenyl)ethoxy]-3-oxo-prop-1-enyl]phenyl] 4-(4,4,4-trifluorobutoxy)benzoate and tetrahydro-5,9-methano-1H-pyrano[3,4-d]oxepin-1,3,6,8(4H)-tetrone in NMP.

Example 22

Photo Alignment Polymer Solution LPP5

(67) 1.7 g (4.3 mmol) of (E)-3-[4-[4-(4,4,4-trifluorobutoxy)benzoyl]oxyphenyl]prop-2-enoic acid (synthesized as described in synthetic examples 1.1 to 1.3) and 1.61 (4.3 mmol) of (E)-3-[4-(4-heptylcyclohexanecarbonyl)oxyphenyl]prop-2-enoic acid (synthesized in analogous manner as described in examples 1.1 to 1.2 of WO2008/145225 A2) are suspended in 60 mL of 4-methyl-2-pentanone and 0.62 g of water. 0.18 g (0.86 mmol) of tetraethylammonium bromine are added to give a white suspension. 5 g (17.3 mmol) of 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane are added dropwise. The mixture is stirred at reflux for 48 h. The suspension is allowed to cool down. 20 mL of tetrahydrofuran and 50 mL of ethyl acetate are added and the mixture is extracted twice with 40 mL of water. The phases are separated and the organic phase is concentrated. The resulting solution is poured slowly into 500 mL of ice cold diisopropyl ether. The solid is filtered off and dried under vacuum to give 5.6 g of polymer.

Formulation Examples 1-21 (F1-F21) and Formulation Comparative Examples 1-3 (FC1-FC3)

(68) Formulations are obtained by mixing the corresponding PAA and/or PAAC with LPP, and diluted to 4% solid content with NMP, gamma-butyrolactone, diethylene glycol diethyl ether and ethylethoxy propionate.

Application Example 1

(69) Test cells are prepared using the “one drop filling method”. The sealant material is printed on the edges of the cell and before curing of the sealing material the liquid crystal is applied on the first substrate. Irradiation with UV light occurs when the second substrate is applied on top of the cell.

(70) Preparation of Test Cells

(71) Formulations F1-F21 or comparative formulations FC1-FC3 are applied to a pair of indium tin oxide (ITO) coated rectangular glass plates with single pixel of 8×8 mm by spin coating at 1200 to 1800 rpm for 30 seconds. The films were subjected to pre-baking for 1.5 minutes at 80° C. and post-baking for 40 minutes at 200° C. The resulting layer thickness is around 100 nm. Both ITO covered glass plates were irradiated with polarised UV-B light at a dose of 22 mJ/cm.sup.2. The direction of incidence light relative to the substrate normal was of 40° and the incidence plane was in parallel to the long side of the substrate. A photo- and/or thermal-curable acrylic resin is applied near the pixel area of one irradiated plate, in form of three stripes, one along the right side at a board to board distance to the pixel of approx. 0.5 mm, and two on the left upper side as well left down side of the cell at a board to board distance to the pixel of approx. 0.5 mm. The acrylic resin stripes mimic a source of contamination. The pair of irradiated plates is then used to build a cell having 4.5 m spacing in an anti-parallel manner such that the irradiated surfaces were facing each other, by using the UV curable sealant Photolec A-785 (manufactured by Sekisui Chemical Co Ltd) as outside frame sealant. The cell is then maintained at room temperature under high vacuum for 14 hours and thereafter filled with TFT liquid crystal mixture MLC6610 from Merck in vacuum at room temperature. The cell annealing and the sealant thermal curing is processed at 130° C. for 30 min.

Application Example 2

(72) Determination of Pre-Tilt Angle θ

(73) Pre-tilt angle evaluation is done by means of the crystal rotation method. Pre tilt angle is measured with respect to the substrate surface.

(74) Pre-tilt angle is defined as an angle from the glass substrate to the average long axis direction of liquid crystal.

(75) Pre-tilt angle θ.sub.0 is measured on the centre position as well as at the two positions distanced by 3 mm from the centre in the direction of the stripes of acrylic resin. The latter are called pre-tilt angles θ.sub.s. At least two cells are made without acrylic resin, while at least three cells are made with acrylic resin. For each cell the lowest value of the two θ.sub.s is considered for the calculation Δθ=θ.sub.0−θ.sub.s. The average values of Δθ=θ.sub.0−θ.sub.s are summarized in Table 1.

Application Example 3

(76) Determination of Voltage Holding Ratio (VHR)

(77) VHR is an electrical characterization method to assess the purity of a liquid crystal display or cell. In the case at hand the measurement is carried out by applying a short voltage pulse of 64-μs duration and 1-V amplitude (V0) to the cell and measuring the remaining voltage (V1) across the cell after a typical frame time of 16.67 ms (corresponding to a cell driving frequency of 30 Hz). The measurement is conducted at a temperature of 60° C. The VHR-value of the cell is calculated by the formula

(78) $\mathrm{VHR}\left[\%\right]=\sqrt{\frac{1-{\left[\frac{V_1}{V_0}\right]}^2}{2\ln \frac{V_0}{V_1}}}100\%$

(79) The ideal VHR-value is 100% and the lower the purity of the cell, the lower is the VHR-value.

(80) TABLE-US-00001 TABLE 1 VHR Δθ (°) PAA LPP PAA/LPP Contamination after Pretilt θ.sub.0 (°) after 140 h Formulation solution solution solid ratio source 140 h after 140 h +/− 3 mm F1 PAA1 LPP1 90:10 not added 98.1 88.28 <0.02 added 97.8 88.20 <0.05 F2 PAA2 LPP1 90:10 not added 98.9 88.31 <0.02 added 97.7 88.10 <0.05 F3 PAA2 LPP1 85:15 not added 98.9 88.35 <0.05 added 98.0 88.28 <0.05 F4 PAA2 LPP2 90:10 not added 99.0 88.23 <0.02 added 96.7 88.25 0.05 F5 PAA3 LPP1 85:15 not added 99.1 88.35 <0.02 added 97.9 88.29 0.08 Compara- PAAC1 LPP1 90-10 not added 99.1 88.29 <0.02 tive 1 FC1 added 97.3 88.16 0.17 F6 PAA4 LPP1 90:10 not added 98.8 88.19 <0.02 added 97.9 88.16 <0.05 F7 PAA4 LPP1 85:15 not added 98.7 88.29 <0.02 added 97.0 88.22 0.06 F8 PAA4 LPP3 85:15 not added 99.0 88.36 <0.02 added 98.3 88.30 <0.05 F9 PAA5 LPP1 85:15 not added 98.8 88.30 <0.02 added 97.3 88.15 <0.05 F10 PAA4 LPP4 90:10 not added 99.0 87.32 <0.02 added 98.3 87.22 <0.05 Compara- PAAC2 LPP1 85:15 not added 98.6 88.32 <0.02 tive 2 FC2 added 97.5 88.25 0.23 F11 PAA6 LPP1 85:15 not added 98.9 88.32 <0.02 added 96.9 88.27 0.16 F12 PAA7 LPP1 85:15 not added 99.0 88.29 <0.02 added 97.1 88.15 0.20 F13 PAA8 LPP1 85:15 not added 98.9 88.24 <0.02 added 97.7 88.18 0.05 F14 PAA9 LPP1 85:15 not added 98.7 88.39 <0.02 (2.4%) added 96.9 88.25 0.15 PAAC2 (97.6%) F15 PAA10 LPP1 85:15 not added 98.4 88.49 0.02 added 96.7 88.43 0.34 F16 PAA11 LPP1 85:15 not added 98.6 88.46 <0.02 added 97.3 88.34 <0.05 F17 PAA12 LPP1 85:15 not added 98.9 88.31 0.07 (2.1%) added 97.3 88.19 0.16 PAAC2 (97.9%) F18 PAA13 LPP1 85:15 not added 99.0 88.30 <0.02 added 96.7 88.22 0.09 F19 PAA14 LPP1 85:15 not added 99.0 88.42 <0.02 added 97.5 88.25 0.16 F20 PAA15 LPP1 85:15 not added 98.8 88.42 0.00 added 97.0 88.29 0.29 F21 PAA4 LPP5 93:7 not added 98.3 87.77 <0.02 added 98.1 87.87 <0.02 Compara- PAAC2 LPP5 93:7 not added 98.4 87.85 <0.02 tive 3 FC3 added 97.8 87.88 0.07 F1 PAA1 LPP1 90:10 not added 98.1 88.28 <0.02 added 97.8 88.20 <0.05 F2 PAA2 LPP1 90:10 not added 98.9 88.31 <0.02 added 97.7 88.10 <0.05 F3 PAA2 LPP1 85:15 not added 98.9 88.35 <0.05 added 98.0 88.28 <0.05 F4 PAA2 LPP2 90:10 not added 99.0 88.23 <0.02 added 96.7 88.25 0.05 F5 PAA3 LPP1 85:15 not added 99.1 88.35 <0.02 added 97.9 88.29 0.08 Compara- PAAC1 LPP1 90:10 not added 99.1 88.29 <0.02 tive 1 FC1 added 97.3 88.16 0.17 F6 PAA4 LPP1 90:10 not added 98.8 88.19 <0.02 added 97.9 88.16 <0.05 F7 PAA4 LPP1 85:15 not added 98.7 88.29 <0.02 added 97.0 88.22 0.06 F8 PAA4 LPP3 85:15 not added 99.0 88.36 <0.02 added 98.3 88.30 <0.05 F9 PAA5 LPP1 85:15 not added 98.8 88.30 <0.02 added 97.3 88.15 <0.05 F10 PAA4 LPP4 90:10 not added 99.0 87.32 <0.02 added 98.3 87.22 <0.05 Compara- PAAC2 LPP1 85-15 not added 98.6 88.32 <0.02 tive 2 FC2 added 97.5 88.25 0.23 F11 PAA6 LPP1 85:15 not added 98.9 88.32 −0.06 added 96.9 88.27 0.16 F12 PAA7 LPP1 85:15 not added 99.0 88.29 −0.06 added 97.1 88.15 0.20 F13 PAA8 LPP1 85:15 not added 98.9 88.24 −0.08 added 97.7 88.18 0.05 F14 PAA9 LPP1 2:83:15 not added 98.7 88.39 −0.02 added 96.9 88.25 0.15 F15 PAA10 LPP1 85:15 not added 98.4 88.49 0.02 added 96.7 88.43 0.34 F16 PAA11 LPP1 85:15 not added 98.6 88.46 −0.05 added 97.3 88.34 <0.05 F17 PAA12 LPP1 1.8:83.2: not added 98.9 88.31 0.07 15 added 97.3 88.19 0.16 F18 PAA13 LPP1 85:15 not added 99.0 88.30 −0.04 added 96.7 88.22 0.09 F19 PAA14 LPP1 85:15 not added 99.0 88.42 −0.02 added 97.5 88.25 0.16 F20 PAA15 LPP1 85:15 not added 98.8 88.42 0.00 added 97.0 88.29 0.29 F21 PAA4 LPP5 93:7 not added 98.3 87.77 −0.05 added 98.1 87.87 −0.01 Compara- PAAC2 LPP5 93.7 not added 98.4 87.85 −0.04 tive 3 FC3 added 97.8 87.88 0.07

(81) As shown in table 1, the formulations according to the present invention stabilize the pre-tilt angle in case of contamination, without diminishing the electro-optical properties of the cell as for example the VHR. The Δθ of the formulations according to the present invention are much lower than those of the comparative examples. Comparative compositions FC1, FC2 and FC3 do not stabilize the pre-tilt angle of liquid crystal upon contamination with the acrylic resin. Stabilization of the pre-tilt angle upon contamination is reached also when an LPP based on a polysiloxane backbone is used or when the LPP contains monomers of formulae (Ia) or (Ib). This demonstrates that all photo-aligning materials can be used in the compositions according to the present invention. The skilled person could have not foreseen that the photoalignment compositions according to the present invention comprising a polymer would have a stabilizing effect on the pre-tilt angle of cells contaminated by an acrylic resin, without affecting the electro-optical properties of the cell, as for example the VHR.