Effect of ionic and nonionic substituents on the electrorheological characteristics of polyaniline derivatives

We report our experimental results on the electrorheological (ER) characteristics of ER fluids consisting of suspensions of semiconducting polyaniline and copolyaniline particles in silicone oil. Ionic sodium diphenylamine sulfonate and nonionic o-ethoxyaniline were introduced to synthesize copolyanilines, i.e. N-substituted copolyaniline and poly (aniline-co-o-ethoxyaniline), respectively. ER fluids using these particles were compared. ER fluids, which contain the ionic copolymer, showed the highest ER performance among polyaniline and its copolymer systems. This result was interpreted in terms of the conductivities of the particles and their dielectric spectra.