Two series of thermotropic liquid crystalline main-chain fluorine-containing polyesters, based on fluorinated alkylene diols and terephthaloyl-bis-(4-oxybenzoylchloride) and its analogue containing nitrogroup in the central phenylene ring were studied by polarizing microscopy, differential scanning calorimetry, viscometry, isothermic diffusion and electric birefringence methods. The upper limit of the fluorinated spacer length, when these polyesters lose their ability to form mesophase was found. It was established that the melting temperatures of the polyesters did not decrease with increasing number of CF$- 2$/ groups in the spacer. The nematic textures of the investigated polymers were observed in cross polarizers. The differences in conformational and electro-optical properties of polyesters with fluoro- and hydrocarbon spacers were found. The dipole mechanism of the polyester molecules orientation in electric field was revealed. Two series of low-molecular-weight liquid crystalline compounds were synthesized to compare their properties with those of the polymers of similar structure. These esters exhibited a tendency to form smectic phase. The influence of the alkyl end group length on the mesomorphic properties of the esters was found.
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