Synthesis of γ-Fe 2 O 3 @SiO 2 @polypyrrole core/shell/shell nanospheres with flexible controllability of electromagnetic properties

A new anchoring method by –SO 3 H groups was proposed to prepare γ-Fe 2 O 3 @SiO 2 @polypyrrole (γ-Fe 2 O 3 @SiO 2 @PPy) nanospheres with core/shell/shell structure. In the reaction process involved, the sulfonic-functionalized γ-Fe 2 O 3 @SiO 2 (γ-Fe 2 O 3 @SiO 2 –SO 3 H) acts as the core for the polymerization of pyrrole. And PPy can be anchored to form on the surface of γ-Fe 2 O 3 @SiO 2 to form γ-Fe 2 O 3 @SiO 2 @PPy nanospheres with the help of the sulfonic groups on the surface of γ-Fe 2 O 3 @SiO 2 . Moreover, flexible controllability of the conductivity and saturation magnetization of the resulting γ-Fe 2 O 3 @SiO 2 @PPy nanospheres can be realized through this method. The resulting electromagnetic γ-Fe 2 O 3 @SiO 2 @PPy nanospheres show a maximum conductivity of 53 S cm −1 and saturation magnetization of 8.17 A m 2 kg −1 . The method reported here may provide an efficient way to realize the best impedance matching between complex permeability and complex permittivity.