Smart monodisperse polystyrene/polyaniline core-shell structured hybrid microspheres fabricated by a controlled releasing technique and their electro-responsive characteristics

We synthesized core/shell structured monodisperse semi-conducting polystyrene/polyaniline (PS/PANI) composite microspheres, and studied their electro-responsive electrorheological (ER) performance under an applied electric field strength when dispersed in silicone oil. An over-layer of the conducting PANI is formed by a controlled releasing process of the aniline pre-adsorbed on the PS seed latex without any surface modification, in which the PS seed microspheres were readily prepared by a dispersion polymerization method. The PS microspheres are observed to be regularly encapsulated with PANI from the morphology test. The ER behaviors of the hybrid microspheres are characterized using a rotational rheometer equipped with a high voltage supplier. The yield stress and flow response as a function of shear rate under certain electric field strengths are investigated using the universal yield stress equation and the Cho-Choi-Jhon model of rheological equation of state, respectively. The relaxation time and achievable polarizability of the fluid from its dielectric analysis were also found to be well correlated with the ER performance of the ER fluid.