Influence of particle size on electrorheological effect of poly(ionic liquid) microsphere suspensions

Hydrophobic poly(ionic liquid) microspheres with different sizes are prepared via cooling assisted phase separation method. The morphology and structure of microspheres are characterized by scanning electron microscope, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The effect of particle size on the electrorheological effect of the poly(ionic liquid) microsphere suspensions is studied by rheological test under electric fields. It shows that the shear stress at zero electric field decreases with the increase of particle size, while yield stress and electric field-induced shear stress increase with the increase of particle size. The electric field dependence of yield stress and electric field-induced shear stress increment is independent of particle size.