Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

A polymer composition, comprising:

• (A) a side chain polymer which is a photosensitive side chain polymer exhibiting liquid crystallinity in a predetermined temperature range and has a repeating unit comprising from 0.1 to 50 mol % of a vertically alignable group;
• and
• (B) an organic solvent;
• wherein the vertically alignable group is
• at least one member selected from the group consisting of alkyl having 6 to 17 carbon atoms:
• wherein component (A) comprises one or more photosensitive sidechains of the following formula:
• wherein A, B, and D each independently represent a single bond, —O—, —CH2—, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, or —O—CO—CH═CH—;
• S represents an alkylene group having 1 to 12 carbon atoms, and a hydrogen atom bonded thereto may be replaced with a halogen group;
• T represents a single bond or an alkylene group having 1 to 12 carbon atoms, and a hydrogen atom bonded thereto may be replaced with a halogen group;
• Y2 represents a group selected from the group consisting of a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and a combination thereof, and hydrogen atoms bonded thereto may be each independently substituted with —NO2, —CN, —CH═C(CN)2, —CH═CH—CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;
• R represents hydroxy;
• P and Q each independently represent a group selected from the group consisting of a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and a combination thereof, and when X is CH═CH—CO—O— or —O—CO—CH═CH—, P or Q on a side to which —CH═CH— is bonded is an aromatic ring;
• and
• l1 represents 0 or 1;
• l2 represents an integer of 0 to 2;
• when both l1 and l2 are 0, A also represents a single bond when T is a single bond;
• when l1 is 1, B also represents a single bond when T is a single bond.