Synthesis and Physical Characterization of Core/Shell Structured Polymeric Microspheres with Polyaniline Shell
Core/shell structured particles with poly(methyl methacrylate) (PMMA) core and conducting polyaniline (PANI) shell were synthesized both with and without surface modification. Initially, monodisperse PMMA microspheres ranging from 6 to 10 micron in diameter as a core material were synthesized by dispersion polymerization, and then PANI was coated on the PMMA core via a chemical oxidation. In the case of surface modification, the pristine PMMA was treated with glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) for swelling agent and crosslinker, respectively. PANI shell was synthesized via grafting polymerization. Various characteristics were examined via SEM, TGA, 13C-NMR and optical microscope, demonstrating its successful formation of core/shell structured PMMA microspheres. These microspheres were also used for their electrorheological (ER) characterization. Yield stress of the ER fluid under an applied electric field was observed to be increased with a particle size, and this result was analyzed via a dielectric spectrum. Furthermore, a universal scaling equation of the yield stress was applied.