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

We report our experimental results on the electrorheological (ER) character istics of ER fluids consisting of suspensions of semiconducting polyaniline and copolyaniline particles in silicone oil. Ionic sodium diphenylamine su lfonate and nonionic o-ethoxyaniline were introduced to synthesize copolyan ilines, i.e. N-substituted copolyaniline and poly (aniline-co-o-ethoxyanili ne), respectively. ER fluids using these particles were compared. ER fluids , which contain the ionic copolymer, showed the highest ER performance amon g polyaniline and its copolymer systems. This result was interpreted in ter ms of the conductivities of the particles and their dielectric spectra.