Well controlled core/shell type polymeric microspheres coated with conducting polyaniline: fabrication and electrorheology

Abstract

We report the fabrication and electrorheology of encapsulated core/shell structured microspherical particles with crosslinked poly(methyl methacrylate) (PMMA) as a core and conducting polyaniline (PANI) as a shell. Monodisperse PMMA particles were synthesized by dispersion polymerization initially, and then PANI was coated on the surface modified PMMA core via a chemical oxidation method for the application of electrorheological (ER) materials under an applied electric field strength. For the surface modification, the pristine PMMA microspheres were treated with ethylene glycol dimethacrylate, glycidyl methacrylate and oxydianiline in sequence as a crosslinking, swelling and grafting agent, respectively. Through this way the well controlled core/shell structure with a thick PANI layer was achieved. ER performance of these obtained microspheres dispersed in a silicone oil was investigated, in which their yield stress was analyzed based on the universal equation as a function of applied electric strength. Interesting shear stress curves observed under various electric field strengths were also found to be fitted well with the Cho–Choi–Jhon model of the rheological equation of state.