Study on a series of main-chain liquid-crystalline ionomers containing sulfonate groups

A series of main-chain Liquid-crystalline ionomers containing sulfonate gro ups pendant on the polymer backbone were synthesized by an interfacial cond ensation reaction of 4,4'-dihydroxy-alpha,alpha'-dimethyl benzalazine, a me sogenic monomer, with brilliant yellow (BY), a sulfonate-containing monomer , and a 1/9 mixture of terephthaloyl and sebacoyl dichloride. The structure s of the polymers were characterized by LR and UV spectroscopies. DSC and t hermogravimetric analysis were used to measure the thermal properties of th ose polymers, and the mesogenic properties were characterized by a polarize d optical microscope, DSC, and wide-angle X-ray diffraction. The ionomers w ere thermally stable to about 310 degreesC. They were thermotropic liquid-c rystalline polymers (LCPs) with high mesomorphic-phase transition temperatu res and exhibited broad nematic mesogenic regions of 160-170 degreesC, and they were lyotropic LCPs with willowy leaf-shaped textures in sulfuric acid . However, the thermotropic liquid-crystalline properties were somewhat wea kened because the concentration of BY was more than 8%. The inherent viscos ity in N-methyl-2-pyrrolidone suggested that intramolecular associations of sulfonate groups occurred at low concentration, and intermolecular associa tions predominated at higher concentration. (C) 2001 John Wiley & Sons, Inc .