Titanate nano-whisker electrorheological fluid with high suspended stability and ER activity

We prepared a new electrorheological (ER) fluid using titanate nano-whiskers as the dispersal phase. The titanate nano-whiskers, which were easy to synthesize by a simple hydrothermal treatment of TiO₂ nano-particles in alkaline solution, possessed a low apparent density of about 1.85 g cm^-3, large length-diameter ratio, and layered tube-like structure bonded loosely with ions by electrostatics. The ER fluid was prepared by dispersion of nano-whiskers in silicone oil with the ultrasonic technique. It was found that the suspended stability of this nano-whisker ER fluid was much better than that of the nano-particle ER fluid when no additive was added to the fluid. No significant sedimentation was found in this nano-whisker ER fluid after several months, due to the supporting effect of the nano-whiskers with large length-diameter ratio, while sedimentation occurred in TiO ₂ nano-particle ER fluid due to aggregation of nano-particles. Under electric field, this nano-whisker ER fluid showed notable ER activity with dynamic yield stress of about 1.1 kPa at 3 kV mm^-1 and 10% particle volume fraction, which outclassed the yield stress (80 Pa) of ER fluid made of the raw material of TiO₂ nano-particles.