Synthesis and characterizations of monodispersed micron-sized polyaniline composite particles for electrorheological fluid materials

Monodispersed micron-sized polyaniline (PANi) composite particles were synthesized by chemical oxidation polymerization of aniline in the presence of functional porous polymer particles considering the surface functionality and the deposition space. The PANi particles formed in the reaction medium deposited onto the porous substrate to produce PANi-coated composite particles. The formation of the composite was confirmed by Fourier transform IR spectroscopy and UV-vis spectroscopy, and their morphological structures were examined by scanning electron microscopy. From the experimental results, it was determined that PANi was successfully coated onto the functional macroporous polymer particles, maintaining the size monodispersity. The electrorheological properties of the suspensions prepared by dispersing the composite particles in silicone oil were investigated under different electric fields. It was found that the fluids showed a great increase in shear stress, exhibiting a dynamic yield stress under high electric fields; however, the shear stress at low electric fields did not show good particle polarization with fluctuating stress values. In addition, the PANi composite particles exhibited different electrorheological behavior according to the particle size.