Main chain polymers containing banana-shaped mesogens: Synthesis and mesomorphic properties

Twelve azomethine polymers containing a banana-shaped mesogen as a repeating unit have been synthesized by polycondensation, and their mesomorphic properties were studied. The solution viscosities were measured in a 0.16 g/dL solution in H2SO4 at 30 degreesC, and the values are in the range 0.37-0.79 dL/g. Polymers obtained were characterized by FT/IR and NMR spectrometry, differential scanning calorimetry (DSC), optical microscopy, and X-ray diffractometry (XRD). The effect of spacer length and lateral substituents on the central core as well as the sidearms of these polymers are described. Of the 12 polymers, eight polymers are found to be thermotropic liquid crystals. Among four polymers with a dioxydodecamethylenene spacer, three polymers exhibited banana phases and one polymer revealed a smectic phase; four polymers with a dioxyhexamethylene spacer showed only a nematic phase. The structures of the banana phases in the polymers are also described.