Cinnamic acid derivative, polymer thereof, and liquid crystal alignment layer comprising cured product thereof

A polymer constituted with a cured product, wherein the cured product has a structural unit represented by the general formula (V):

• wherein Sp1 and Sp2 each represent a spacer unit, A01 and A02 each independently represent a group selected from the group consisting of:
• (a) a trans-1,4-cyclohexylene group wherein one methylene group or two or more non-adjacent methylene groups present in this group may be substituted with —O—,—NH—, or —S—,
• (b) a 1,4-phenylene group wherein one or two or more —CH═'s present in this group may be substituted with —N═, and
• (c) a 1,4-cyclohexenylene group, a 2,5-thiophenylene group, a 2,5-furanylene group, a 1,4-bicyclo(2.2.2)octylene group, a naphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, a decahydronaphthalene-2,6-diyl group, and a 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a), (b), or (c) may be each unsubstituted or may have one or more hydrogen atoms substituted with a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group,
• X1, X2, Y1 and Y2 each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, or an alkyl group having 1 to 20 carbon atoms, but a hydrogen atom in the alkyl group may be substituted with a fluorine atom, and one CH2 group or two or more non-adjacent CH2 groups may be substituted with —O—, —CO—O—, —O—CO—, —CH═CH—or a combination thereof,
• Z is represented by the general formula (IIa) or (IIb):
• in which the dashed line represents a bond to a carbon atom, to which Z is bonded, and
• R1 R2 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 30 carbon atoms, wherein one —CH2—group or two or more non-adjacent —CH2— groups in R1 and R2 may be substituted with —O—, —CO—, —CO—O—, —O—CO—, —CO—NH—, —NH—CO—, —NCH3—, —CH═CH—, —CF═CF—, —C≡C—, or a combination thereof, wherein one or two or more —CH2— groups in R1 and R2 may be each independently substituted with a cycloalkyl group with a 3- to 8-membered ring, and a hydrogen atom in R1 and R2 may be substituted with an alkyl group having 1 to 20 carbon atoms, a cyano group, or a halogen atom,
• W represents —O— or —NR3—, in which R3 represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, or a cycloalkyl group with a 3- to 8-membered ring, which may have the alkyl group interposed therein as a linking group, a hydrogen atom in the alkyl group may be unsubstituted or may be substituted with a fluorine atom or a chlorine atom, a hydrogen atom in the cycloalkyl group may be unsubstituted or may be substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine atom, or a chlorine atom, and r and t each independently represent 1 or 2, Mb and Md each represent a monomer unit of the polymer, y and w each represent a molar fraction of the copolymer, each satisfying 0<y≤1 and 0≤w<1, n represents 4 to 100,000, the order in which Mb and Md are arranged may be the same as or different from that shown in the formula, and the monomer units of Mb and Md may be each independently constituted with one or two or more different units.