Preparation of montmorillonite/titania nanocomposite and enhanced electrorheological activity

We prepared a new type of electrorheological particle composed of TiO ₂ nanocrystallites-coated montmorillonite (MMT/TiO₂) nanocomposite by the sol-gel technique. The characterizations including TGA, XRD, TEM, SEM, EDS, and FTIR showed that TiO₂ was deposited on the surface of the MMT flakes with anatase nanocrystallite. An obviously enhanced ER effect was found in the MMT/TiO₂ nanocomposites based ER fluids compared with pure MMT and TiO₂. Furthermore, the temperature and sedimentation stabilities of the MMT/TiO₂ ER fluids had also been improved greatly. Interestingly, the content of TiO₂ was demonstrated to have an important influence on the ER effect. When the content of TiO ₂ was about 20 wt%, the ER effect of MMT/TiO₂ ER fluid reached its maximum, which was about 5 times that of pure MMT ER fluid and 27 times that of pure TiO₂ ER fluid. Based on dielectric analysis, the significant ER enhancement by formation nanocrystallites-coated montmorillonite was attributed to the enhanced interfacial polarization in this nanocomposite particle due to the effective limitation of the long-range drift of active ions in montmorillonite particles.