Structural isomerism in Polycondensates. Part IV. Synthesis and characterization of liquid crystalline poly(azomethines) and low molecular weight model compounds

Abstract

AbstractWith the aim to investigate the influence of structural isomerism on the mesomorphic thermal stability in main chain thermotropic polycondensates, a series of poly(azomethines) and low molecular weight models have been prepared. The model compounds exhibit smectic and/or nematic mesophases whose stabilites are very sensitive to structural modifications. On the basis of the above results, monomers 2, 5, 6, 8, 9, 23, 25, and 26 were selected to synthesize oligomers 27–23. The oligomer 33 obtained from the nonsymmetric diamine 23 has a lower melting point than the symmetric oligomer 28, but a similar liquid crystalline range.