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

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:
• 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 H2N—A—NH2 diamine represented by a compound of formula (IVa), (IVb), (IVc), (VIII), (IX), (XII), (XIII), (XIV), (XV), (XVIIIa) or (XVIIIb):
• wherein X1, X1, X3, X4, X5, X6, X10, X11, X13 and X14 are linking groups which are selected from a single bond, unsubstituted or mono- or poly-substituted C1-C8 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, CH2, O or S;
• and
• wherein repeating structural units (IIIa) and (IIIb) are represented by formulae:
• 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.