Electrorheological activity generation by graphene oxide coating on low-dielectric silica particles

A recent challenge in the field of electrorheology is to generate or to enhance the electrorheological (ER) activity of an inactive or lowly active suspension using core-shell structured particles. Here we illustrate the application of graphene oxide (GO) adsorbed onto the silica particles to make the core-shell structure. The suspension exhibited significant changes in shear viscosity upon the application of an external electric field. The suspension of the core-shell particles also exhibited an occurrence of ER activity enhancement more than an order of magnitude, compared to that of pure silica suspension. The yield stress of this system scales as tau(y) proportional to E-1.5. The dielectric relaxation study revealed that the ER activity was due to the fast occurrence of polarization in the GO-Si suspension. The suspension showed good sensitivity and stability under the electric field. These findings open up the possibilities for design of smart suspensions with high ER responses.