Synthesis of γ-Fe2O3@SiO2@polypyrrole core/shell/shell nanospheres with flexible controllability of electromagnetic properties

Abstract

A new anchoring method by –SO₃H groups was proposed to prepare γ-Fe₂O₃@SiO₂@polypyrrole (γ-Fe₂O₃@SiO₂@PPy) nanospheres with core/shell/shell structure. In the reaction process involved, the sulfonic-functionalized γ-Fe₂O₃@SiO₂ (γ-Fe₂O₃@SiO₂–SO₃H) acts as the core for the polymerization of pyrrole. And PPy can be anchored to form on the surface of γ-Fe₂O₃@SiO₂ to form γ-Fe₂O₃@SiO₂@PPy nanospheres with the help of the sulfonic groups on the surface of γ-Fe₂O₃@SiO₂. Moreover, flexible controllability of the conductivity and saturation magnetization of the resulting γ-Fe₂O₃@SiO₂@PPy nanospheres can be realized through this method. The resulting electromagnetic γ-Fe₂O₃@SiO₂@PPy nanospheres show a maximum conductivity of 53 S cm⁻¹ and saturation magnetization of 8.17 A m² kg⁻¹. The method reported here may provide an efficient way to realize the best impedance matching between complex permeability and complex permittivity.