ELECTRORHEOLOGY OF MONODISPERSE CORE/SHELL STRUCTURED PARTICLE SUSPENSIONS

초록

As a candidate of a novel ER material of polarizable particle dispersed in a non-conducting medium, core/shell composite particles (PAPMMA) with poly(methyl methacrylate) (PMMA) core and polyaniline (PANI) shell were prepared with and without surface modification, and used as a dispersed phase. PAPMMA particles, obtained by a dispersion polymerization method, were spherical and possessed a monodisperse particle size distribution. PANI shell was introduced on the surface of PMMA via an in-situ polymerization of aniline by adding an oxidant in an aqueous acidic solution as well as a grafting polymerization method of PANI on surface of acrylic microspheres having aniline moieties. Yield stress of PAPMMA suspensions under an applied electric field was observed to be increased with a particle size, and this result was analyzed via a dielectric spectrum. Dielectric spectra of ER fluids provide insight into the understanding both electrical polarization properties and flow behaviors for the PAPMMA based ER fluids.