A polyamic acid is herein disclosed which contains a structural unit represented by the formula \x9b2a! ##STR1## wherein m is an integer of 1 to 20; n is an integer of 1 to 2; and R.sup.2 is an alkyl group or an alkoxy group having 1 to 20 carbon atoms. Furthermore, a polyamic acid composition is also disclosed which comprises the polyamic acid containing the structural unit represented by the formula \x9b2a! and another polyamic acid containing a structural unit other than mentioned above. By heating the polyamic acid or the polyamic acid composition at a low temperature for a short time, a liquid crystal alignment film can be obtained therefore.
A polyimide comprises a reaction product of at least one dianhydride and at least one diamine, wherein the at least one diamine contains a pendent mesogenic group. A method for inducing a predetermined orientation of a liquid crystal material is also disclosed. The method includes applying an alignment layer material to a substrate and buffing the alignment layer material, thereby providing an alignment layer with a pre-tilt angle, wherein the alignment layer material is a reaction product of at least one dianhydride and at least one diamine, wherein the at least one diamine contains a pendent mesogenic group.