Photoaligning materials

A siloxane polymer comprising a structural unit of formula (I′):

• wherein
• Ra represents OH, Cl, substituted or unsubstituted alkoxyl group having 1 to 20 carbons, alkyl group having 1 to 20 carbons, or aryl group having 1 to 20 carbons;
• S1 represents a single bond or straight-chain or branched, substituted or unsubstituted C1-C24alkylene in which one or more —C—, —CH—, —CH2— group may be replaced by a heteroatom;
• z is an integer from 0 to 15;
• Z1 represents a single bond, or a substituted or unsubstituted aliphatic or alicyclic group of C3 to C12;
• n0 is an integer of 0;
• n1 is an integer of 1;
• n2 is an integer of 1;
• x0 is an integer from 1 to 2;
• X, Y each independently from each other represents H, F, Cl, CN;
• S2 represents a straight-chain C2-4alkylene in which several —CH2— groups are replaced by an unsubstituted or substituted cyclohexylene, and one —CH2— group is replaced by —CO—O—, or —O—CO—;
• E represents O;
• A represents halogen, H or substituted or unsubstituted C1-C24 alkyl, a substituted or unsubstituted C1-C24 alkenyl, a substituted or unsubstituted C1-C24 alkynyl, a carboxylic acid, or C1-C24 alkoxy, wherein one or more, —C—, —CH—, —CH2—, group may independently from each other be replaced by a heteroatom;
• Z2 represents a chemical group having a delocalisation of its electronical density and/or inducing a delocalisation of the electronical density of its neighboring atom;
• and T represents an unsubstituted or substituted, straight-chain C1-C16alkylene.