Co-polymers of formula: (φC(CH3)NN(CH3)CφOOC(CH2)nCOO)x (n = 6 (25%) 10 (75%); n = 6 (50%), 10 (50%); n = 6 (75%), 10 (25%)) have been prepared and some of their properties studied by X-ray diffraction, differential scanning calorimetry and optical methods. Like the corresponding homo-polymers (n = 6 (100%); n = 10 (100%)) the co-polymers show thermotropic liquid crystal behaviour. Isotropization temperatures and molar isotropization enthalpies change regularly with composition but appear to be independent of any thermal treatment that does not involve chemical decomposition of the samples. The range of thermal stability of the mesophase is wider for the co-polymers than for the homo-polymers with a maximum of ∼ 150 K for the 50/50 composition. Although the molar isotropization entropy is relatively large, the mesophase of the 50/50 co-polymer appears, from X-ray diffraction measurements, to be nematic. By comparison of the molar isotropization entropies, the same conclusion is probably valid for the co-polymers themselves. The mesophasic structure is preserved (frozen) at room temperature by quenching the fluid liquid crystal phase. This feature is particularly evident for the 50/50 co-polymer. © 1979.
