Polypyrrole-Fe ₂ O ₃ Nanocomposites with High Dielectric Constant: In Situ Chemical Polymerisation

Novel nanocomposites of polypyrrole (PPy) dispersed with iron oxide (Fe ₂ O ₃ ) particles have been synthesised by in situ chemical oxidative polymerisation of pyrrole in the presence of ammonium persulfate (APS) as an oxidising agent. The concentration of Fe ₂ O ₃ was varied between 10-50wt% of PPy. The simultaneous polymerisation of pyrrole and oxide addition led to the complete synthesis of nanocomposites. A maximum dielectric constant of ∼28500 was observed at 20wt% of Fe ₂ O ₃ . The nanocomposites were characterised by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis confirmed the structure and crystallinity of the nanocomposites, and a strong interaction between PPy and Fe ₂ O ₃ particles was observed by FTIR technique. SEM and TEM images showed that Fe ₂ O ₃ particles had been coated with PPy by establishing a network during the polymerisation process. The values of dielectric constant were obtained from capacitance measurements. The value of dielectric constant for nanocomposites with 20wt% of Fe ₂ O ₃ was observed to be almost 12 times that of the pure PPy matrix. The high value of dielectric constant indicated a high packing density of Fe ₂ O ₃ particles in PPy matrix. These nanocomposites have potential applications in electronic or biomedical devices.