Electroactive response of mesoporous silica and its nanocomposites with conducting polymers

Abstract

Electroactive response of suspensions of mesoporous silica and its nanocomposites with conducting polyaniline and copolyaniline inside its channels were examined under an applied electric field, mainly focusing on their rheological characteristics. Initially these conducting polymer/mesoporous silica nanocomposites were synthesized and their physical properties were studied by scanning electron microscopy, transmission electron microscopy and N 2 -adsorption isotherm. Both mesoporous silica and its nanocomposites were then adopted as an electrorheological (ER) material, being dispersed in silicone oil. Typical ER behaviors of shear stress curve as a function of both applied electric field and shear rate were observed for these ER systems. In the absence of an electric field, the suspensions behaved almost like Newtonian fluids. However, when an electric field was applied to the suspension, their shear stresses increased with a shear rate, demonstrating a yield stress. Comparing with ER fluids based on mesoporous silica and polyaniline, the polyaniline/mesoporous silica based ER fluid showed enhanced ER performance due to the anisotropic characteristics of electrical properties of the polyaniline/mesoporous silica particles. In addition, it was found that the shear stress model (Cho-Choi-Jhon model) gave a good representation of the flow curves of these nanocomposite systems.