Synthesis and electrorheological characteristics of polyaniline-titanium dioxide hybrid suspension

Conducting polyaniline (PANI)/titanium dioxide (TiO2) hybrid particles were synthesized via an oxidation polymerization in the presence of TiO2, and their electrorheological (ER) characteristics were examined, since the formation of an organic/inorganic hybrid exhibits various advantages from the combination of their unique properties as a part of our efforts to find highly potential ER-active particles using conducting polymers. The TiO2 nanoparticles possess a relatively high dielectric constant which is important for polarization in the ER response, in which the ER fluids are a class of colloidal suspensions which show a transition from a liquid-like to a solid-like state under an applied electric field. Synthesized PANI/TiO2 composites in this study were characterized by an FT-IR, thermogravimetry analysis, and scanning electron microscopy. We then prepared the PANI/TiO2 composites-based ER suspension with insulating oil and investigated its ER behavior as a function of shear rate under an applied electric field. The fast relaxation time of PANI/TiO2 hybrid was expected to enhance electrostatic force over shear force under a shear flow, showing the improved ER performance. Furthermore, it was also found that the properties of TiO2 affect the dielectric of PANI/TiO2 composites to give better ER properties.