Synthesis and electrorheological characteristics of sea urchin-like TiO₂ hollow spheres

TiO₂ hollow microspheres with sea urchin-like hierarchical architectures were synthesized by a simple hydrothermal method. The as-synthesized hollow microspheres with hierarchical architectures consisting of many rhombic building units exhibit high specific surface area. Electrorheological (ER) properties of hierarchical hollow TiO₂-based suspension were investigated under steady and oscillatory shear. The hollow TiO₂-based suspensions show much higher yield stress and elasticity than pure TiO₂ suspension at the same electric field strength. This phenomenon was elucidated well in view of their dielectric spectra analysis. The sea urchin-like architectures result in stronger interfacial polarization of hollow TiO₂ suspension upon an electric field, showing higher ER activity. Also, hollow interiors of TiO₂ particles increase the long-term stability of suspensions and further merit the ER effect.