Synthesis and electrical response of polyaniline/poly(styrene sulfonate)-coated silica spheres prepared by seed-coating method.

The polyaniline/poly(styrene sulfonate) (PANI/PSS)-coated silica spheres with three different sizes (50, 100, and 250 nm) are fabricated through seed-coating method and adopted as dispersing materials for electrorheological (ER) fluids to examine the influence of particle diameter on ER activity. Interestingly, the ER properties of PANI/PSS-coated silica spheres exhibit a dependence on their size. Performances of PANI/PSS-coated silica spheres-based ER fluids enhanced with decreasing the diameter of particle. It is believed that the size effect played a dominant role in enhancing the performance of ER fluid. Furthermore, the fibrillation phenomenon of prepared PANI/PSS-coated silica spheres-based ER fluid was observed via an optical microscope in the applied electric field. Sedimentation properties were also analyzed to provide additional insight into the size effect of ER fluids.