Thermotropic liquid crystalline polymer. III. Synthesis and properties of poly(amide‐azomethine‐ester)

A series of novel dialdehydes as new monomers, 4,4′‐diformyl‐α,ω‐diphencarbonylalkane, 4,4′‐diformyl‐3,3′‐methoxy‐α,ω‐diphencarbonylalkane, and 4,4′‐diformyl‐3,3′‐ethoxy‐α,ω‐diphencarbonylalkane, was prepared from aliphatic diacid chloride with p‐hydroxybenzaldehyde, vanillin, and 3‐ethoxy‐4‐hydroxybenzaldehyde, respectively. A series of poly(amide‐azomethine‐ester)s was prepared by condensation of 4,4′‐diaminoanilide with 4,4′‐diformyl‐α,ω‐α,ω‐diphencarbonylalkane, 4,4′‐diformyl‐3,3′‐methoxy‐α,ω‐diphencarbonylalkane, and 4,4′‐diformyl‐3,3′‐ethoxy‐α,ω‐diphencarbonylalkane, respectively. Their thermotropic liquid crystalline properties were examined by DSC microscope observations. In most cases, the mesophase extends up to ca. 288–380°C, where thermal decomposition prevents further observation.