Abstract: A diamine includes a structure of formula (I), wherein X and Y are independently a divalence group selected from the group consisting of: —O—, —(C?O)—O—, —O—(C?O)—, —(C?O)—NH—, and —NH—(C?O)—; and R has a structure of formula (II): wherein R1, R2, R3, R4, R5, m, and n are as defined in Claim 1. A polyamic acid is prepared by reacting a diamine reactant including the aforesaid diamine of formula (I) with a tetracarboxylic dianhydride reactant. A liquid crystal orienting film contains a polyimide converted from the aforesaid polyamic acid.

Abstract: A diamine includes a structure of formula (I), wherein X and Y are independently a divalence group selected from the group consisting of: —O—, —(C?O)—O—, —O—(C?O)—, —(C?O)—NH—, and —NH—(C?O)—; and R has a structure of formula (II): wherein R1, R2, R3, R4, R5, m, and n are as defined in Claim 1. A polyamic acid is prepared by reacting a diamine reactant including the aforesaid diamine of formula (I) with a tetracarboxylic dianhydride reactant. A liquid crystal orienting film contains a polyimide converted from the aforesaid polyamic acid.

Abstract: A polyamic acid-based composition includes: a polyamic acid A prepared by a process including reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine; and a polyamic acid B prepared by a process including reacting an aliphatic tetracarboxylic dianhydride, an aromatic diamine having a side chain, and a non-aromatic diamine. A liquid crystal orienting film is formed by a process including: preparing a mixture containing the aforesaid polyamic acid-based composition and a solvent; coating the mixture onto a substrate so as to form a film on the substrate; and heating the film so as to convert polyamic acid of the polyamic acid-based composition into polyamide.