Synthesis and Characterization of Certain Poly(Ester Amides) from 2,5-Pyridine Dicarboxylic Acid with Photoactive Liquid Crystalline Properties

Poly (ester amides) (PEAs) are considered to be an important class of polymeric materials in recent years as they possess polyester and polyamide building blocks in a single molecule. A new series of four photo-cross-linkable thermotropic liquid crystalline poly(ester amides) were synthesized by direct polycondensation of 2,5-pyridine dicarboxylic acid with two different varying diols and diamines. The two diamines employed in the synthesis were 4,4’-diamino diphenyl methane and 1,4-diamino benzene. The arylidene diols 2,5-bis(4-hydroxy-3- methoxybenzylidene)cyclopentanone and 2,6-bis(4-hydroxy-3-methoxybenzylidene) cyclohexanone were also used. The synthesized poly(ester amides) were characterized by qualitative solubility test, FT-IR, 1H and 13C-NMR spectra. The monomeric moieties were found to be well incorporated in the polymer backbone. The molecular weight of the polymer was assessed by gel permeation chromatography (GPC). The thermal phase transition behavior and liquid crystallinity of the poly(ester amides) were investigated by differential thermogravimetry (DTG) and hot stage optical polarized microscopy (HOPM) respectively. Interestingly these poly(ester amides) in DMAc solution were found to possess photo-crosslinking characteristics when irradiated by UV light. These polymeric materials may find utility value in optical information storage devices. The resulting polymers showed good solubility in polar, aprotic solvents and the inherent viscosity data reveal that these polymers are of high molecular weight.