Dispersion stability and electrorheological properties of polyaniline particle suspensions stabilized by poly(vinyl methyl ether)

In the present article, a novel method of stabilization of a semi conductiv e polyaniline particle nonaqueous suspension of electrorheological (ER) mat erials was introduced. Using as the steric stabilizer poly(vinyl methyl eth er) (PVME), a dispersion polymerization of aniline was performed and stable aqueous dispersions of the polyaniline were obtained. However, a stable co lloidal suspension of polyaniline in silicone oil medium can be obtained on ly with a low concentration of PVME (0.75%), although the average size of t he individual, redispersed particles in oil generally decreased with increa sing concentration of PVME. At higher concentrations of PVME, formation of highly packed particle aggregates was investigated, as seen in the scanning electron microscopy images. The polyaniline suspension stabilized by 0.75% PVME content exhibited the best dispersing state and, therefore, showed th e highest zero-field viscosity. Such a well-stabilized polyaniline suspensi on also showed the maximum ER property, namely the largest normalized yield stress in an electric field, (C) 2001 Academic Press.