Wettability of bionic nanopapilla particles and their high electrorheological activity

Inspired by the nano- and microscale structure of biological surfaces, a kind of nanopapilla particle possessing both nano- and microscale structure has been prepared via a hydrothermal method. The nanopapilla particles have been analyzed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) methods, energydispersive spectroscopy (EDS), X-ray diffraction (XRD), etc. The results show that TiO ₂ nanopapillae are radially distributed on the surface of thin-flake kaolinite. The BET surface area and the wettability of the nanopapilla particles show a marked improvement compared to kaolinite. Moreover, the oleophilic ability of the kaolinite/TiO₂ nanopapilla particles spurs a very high electrorheological activity, which is about fifty times that of pure kaolinite. It is suggested that the significant electrorheological improvement can be attributed to the enhanced dielectric properties of the nanopapilla-particle electrorheological fluid.