Electrorheology of suspensions of mesostructured and mesoporous silica in poly(dimethylsiloxane)

The effect of electric fields on the viscosity and shear stress of dispersions of mesostructured silicon dioxide powders and the products of their thermal treatment, that is, mesoporous silicas, in silicone oil is investigated. Mesostructured silicon dioxide powders are prepared using different structuring reagents, namely, octylamine, dodecylamine, and polyethylenimine. It is shown that the shear stresses developing in systems containing mesostructured powders as dispersed phases under the action of electric fields are several times higher than those in dispersions of mesoporous materials. The shear stresses developing in the systems containing powders of mesostructured materials as dispersed phases under the effect of electric fields depend on the nature of organic substrates present in pores and the conductivity of the systems. Electrorheological effect in dispersions of mesoporous silicas slightly depends on the structure of the materials. The observed synergism may be related to the interactions between the components of a mesostructured material, which manifest themselves as a rise in interfacial polarization. The stress-strain curves were measured upon tensile and compression in electric fields of different strengths.