Synthesis of P(St-MAA)-Fe3O4/PPy core–shell composite microspheres with conductivity and superparamagnetic behaviors

Styrene (St) and methacrylic acid (MAA) copolymers were synthesized by emulsion polymerization using Fe3O4 particles modified by oleic acid as central components. P(St-MAA)-Fe3O4/PPy (polypyrrole) core–shell composite microspheres with conducting and supermagnetic behaviors were obtained via in situ chemical oxidative polymerization on the surface of the P(St-MAA)-Fe3O4 magnetic composite microspheres. The –COOH groups in the composites acted as co-dopants in the formation of PPy and adsorbed the pyrrole monomers onto the surface of P(St-MAA)-Fe3O4. The P(St-MAA)-Fe3O4/PPy composite microspheres have been extensively characterized by transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The Fe3O4 particles were coated within P(St-MAA) polymers when the volume ratio of MAA to St was maintained at 1:5 during the co-polymerization process. The P(St-MAA)-Fe3O4/PPy multi-component composite microspheres show excellent superparamagnetism. The electrical conductivity of the composite microspheres largely depended on the PPy loading amount in the outer layer.