A series of poly(ethylene oxide) (PEO)/organoclay nanocomposites have been prepared via a solvent casting method. Using three different organoclays modified with the alkylammonium salts, the effect of surfactants on organoclay surfaces in polymer/organoclay nanocomposites was investigated by focusing on two major aspects:  internal structure analysis and rheological measurement of the nanocomposites. The d spacings of both the pure PEO and intercalated organoclay were examined via X-ray diffraction analysis, and the microstructure of these nanocomposites was examined by transmission electron microscopy. Rheological properties of these nanocomposites exhibited different behavior with different modifier concentrations and surfactant sizes (chain lengths). To analyze the non-Newtonian flow behavior, we fitted shear viscosity data via the Carreau model, showing that steady shear viscosity and power-law behavior increase with organoclay content. Hysteresis phenomenon was also enhanced with organoclay content, and the increase in the storage/loss moduli and interactions among organoclay platelets were observed with organoclay content. The enhanced thermal stability of the nanocomposites by organoclay was also observed.

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The spherical, monodisperse polymer microshperes (PAPMMAs) consisting of a poly(methyl methacrylate) (PMMA) core and a polyaniline (PANI) shell were prepared and adopted as dispersed materials for electrorheological (ER) fluids, in which electrical conductivity was originated primarily from the surface-coated conducting PANI layer. These surfaces were rough and irregular. Three different core sizes of PAPMMAs (2, 4.5, and 9 μm) with the same weight ratio of PANI, the larger core having the thicker PANI shell, were prepared. PAPMMAs that have similar shell thicknesses but different core sizes were also prepared in order to examine the particle size effect on ER performance. Performances of PAPMMA-based ER fluids were enhanced with increasing core particle size. The same result was obtained for the PAPMMA systems having the same shell thickness. Dielectric spectra of these ER fluids were found to provide additional information on both analyzing their electrical polarization properties and interpreting the flow behavior of the PAPMMA-based ER fluids.