Electrorheology of a mesoporous silica having conducting polypyrrole inside expanded pores

A pore-expanded mesoporous silica (MCM-41-E) having particles of conducting polypyrrole (PPY) included inside its uniformly aligned one-dimensional channels was prepared, and their electrorheological (ER) characteristics when dispersed in a silicone oil were investigated. Both N2-adsorption isotherm and SEM images were employed to confirm the successful formation of PPY/MCM-41-E nanocomposite. The XRD also provided an additional information on the properties of the synthesized nanocomposite material. The nanocomposite showed typical ER characteristics. Shear stress curve was more accurately described by using the rheological constitutive equation (CCJ model) we proposed compared with the Bingham fluid model. Yield stress which increases with applied electric field strength was analyzed based on the universal yield stress equation we suggest as a function of applied electric field strength. It was found that the universal yield stress equation collapses these data onto a single curve well in the case of PPY/MCM-41-E nanocomposite based ER fluid.