A novel thermotropic liquid crystalline polymers poly{3-benzylidene amino-4-hydroxybenzoic acid (3,4-BAHBA)-co-trans-4-hydroxycinnamic acid (4HCA: trans-coumaric acid)} (Poly(3,4-BAHBA-co-4HCA)), was synthesized by the thermal polycondensation of 4HCA and 3,4-BAHBA, which was synthesized by a reaction of 3-amino-4-hydroxybenzoic acid (3,4-AHBA) with benzaldehyde. When the 4HCA compositions of P...