Liquid crystalline polymers V. Thermotropic liquid crystalline poly (azomethine-ether)s containing a cycloalkanone moiety in the polymer backbone

A new homologous series of thermotropic liquid crystalline poly (azomethine -ether)s was synthesized by solution polycondensation of various diformyl-a lpha,omega-diphenoxyalkanes, I-VIII with 2,5-bis (m-aminobenzylidene) cyclo pentanone, XI and 2,6-bis (m-aminobenzylidene)cyclohexanone, XII. The inher ent viscosities of the polymers were in the range 0.34-0.75 dI g(-1). The m esomorphic properties were studied as a function of the diphenoxyalkane spa cer length. Analyses by DSC and optical polarized microscopy demonstrated t hat the poly(azomerhine-ether)s form nematic mesophases over wide temperatu re ranges. The poly(azomethine-ether) a based on the cyclohexanone moiety h ad better thermal stabilities than the corresponding poly (azomethine-ether )s based on cyclopentanone.