Synthesis and thermal properties of side-chain liquid crystalline poly[1-({(4-methoxyazobenzene-4'-oxy)alkyl}thio)-2.3-epoxypropane]s

摘要

A novel series of side-chain liquid crystalline copolymers, i.e. poly-[1-({(4-methoxyazobenzene-4'-oxy)alkyl}thio)-2.3-epoxypropane]s, were synthesised in which the number of methylene units in the alkyl group of the side chain varies from 3 to 6. The structures of compounds obtained were characterised by elemental analysis and 1H NMR spectroscopy. Thermal properties were investigated using polarising optical microscopy, differential scanning calorimetry and X-ray diffraction analysis. The synthesised thiols and corresponding polyepichlorohydrin-based copolymers exhibited thermotropic liquid crystalline behaviour and nematic phases with schlieren textures. The thiols have lower transition temperatures than the corresponding copolymers. In addition, the degree of substitution of the copolymers synthesised increased with an increase in number of methylenes in the side chain. The phase transition temperatures increased and the mesomorphic temperature ranges widened with the increasing degree of substitution of the copolymers.