Method for the preparation of photoaligning polymer materials and compositions

Polymer comprising repeating structural units of formula (I)

• wherein:
• M1 is acrylate, methacrylate or styrene
• ring A signifies phenylene which is unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, pyridine-2,5-diyl, pyrimidine-2,5-diyl, or cyclohexane-1,4-diyl;
• ring B signifies phenylene which is unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,4- or 2,6-naphthylene, or cyclohexane-1,4-diyl;
• Y1, Y2 each independently signify a single covalent bond, —CH2CH2—, —O—, —CF2O, —OCF2—, —CH2—O—, —O—CH2—, —CO—O— or —O—OC—;
• ring C signifies phenylene which is unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-furanylene, or 1,4- or 2,6-naphthylene;
• Z signifies —O— and
• S1 is a spacer unit;
• and
• D is a C1-C3 straight-chain or branched alkylene chain which contains one or more siloxane moieties, and
• m and n signify a whole number of 0 to 4.