Wormhole-like mesoporous Ce-doped TiO₂: A new electrorheological material with high activity

This paper describes a new class of electrorheological (ER) active material composed of wormhole-like mesoporous Ce-doped TiO₂ particles, which were synthesized using long-chain octadecylamine and non-ionic poly(ethylene glycol) as templates followed by a sol-gel process. TEM, XRD and XPS demonstrated that the material possessed disordered wormhole-like mesoporous structure and an anatase framework. Electrorheological experiments showed that suspensions made of such particles with silicone oil had a high static yield stress of 8.7 and 14.0 kPa at 3 kV mm^-1 dc electric field when the particle volume fractions were 27 and 34%, respectively. The latter value is 25 times higher than that of pure TiO₂ and twice as high as that of single-doped TiO₂ without mesophases reported in our previous works. Furthermore, this mesoporous-doped TiO₂ suspension also showed good temperature and dispersion stability. Therefore, not only could Ce-doping improve the ER activity of TiO₂, but also the presence of mesoporous structure further enhances it. The combination of both factors may provide a novel way to develop high-performance ER materials.