A series of main-chain liquid-crystalline polymers (LCPs) with pendant sulfonic acid groups have been synthesized by use of biphenyl-4,4 0 -diol, 6,7-dihydroxynaphthalene-2-sulfonic acid, and bis(4-(chlorocarbonyl)phenyl) decanedioate in a one-step esterification reaction. Emeraldine base form of polyaniline (PAN) is doped by the synthesized sulfonic acid-containing LCPs to obtain PAN-LCP ionomers. A series of electrorheological (ER) fluids are prepared using the synthesized PAN-LCP ionomers and silicone oil. The chemical structure, liquid-crystalline behavior, dielectric property of LCPs, and PAN-LCP ionomers, and ER effect of the ER fluids are characterized by use of various experimental techniques. The synthesized sulfonic acid-containing LCPs and PAN-LCP ionomers display nematic mesophase. The PAN-LCP ionomers show a slight elevation of glass transition temperatures and decrease of enthalpy changes of nematic-isotropic phase transition compared with corresponding sulfonic acid-containing LCPs. The relative permittivity of the PAN-LCP ionomers is much higher than that of the corresponding sulfonic acid-containing LCPs. The ER effect of the PAN-LCP ionomer dispersions is better than PAN dispersions, suggesting a synergistic reaction should be occurred among liquid crystalline component, and PAN part under electric fields.
A novel kind of metallo-phthalocyanine derivative, zinc 2,9,16,23-tetraaminophthalocyanine perfluorooctanoate (Zn-APc-pFOA), was synthesized from zinc tetraaminophthalocyanine and perfluorooctanoic acid. The chemical structure, liquid crystalline behavior, and electrorheological properties were characterized by the use of various experimental techniques, methods, and instruments, including FT-IR and UV-vis spectroscopy, 1 H-NMR, x-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, the four-point method, a relative permittivity test instrument, and a rotating viscometer. Zn-APc-pFOA shows a discotic hexagonal columnar mesophase over a wide temperature range. The dielectric constant and conductivity of Zn-APc-pFOA are 11.4 and 6.34 × 10 −3 S cm −1 , respectively. The 20 V% silicone oil-Zn-APc-pFOA fluid shows an electrorheological (ER) effect. Zn-APc-pFOA is a semiconductor with a high dielectric constant, causing a mismatch of conductivity and dielectric constant between the Zn-APc-pFOA and silicone oil. Furthermore, some synergistic effect could occur between the semiconducting property and the molecular orientation of the discotic liquid crystals in Zn-APc-pFOA suspensions, resulting in a high ER effect.
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