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Keywords:

  • liquid crystals;
  • polyesters;
  • functionalization of polymers

ABSTRACT

A series of main-chain liquid-crystalline polymers (LCPs) with pendant sulfonic acid groups have been synthesized by use of biphenyl-4,4′-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. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3395–3403, 2013