A complex impedance spectroscopy study on PVDF/PANI/CoFe₂O₄ composites

Abstract The synthesis of polymer composites consisting of conducting polyaniline (PANI), cobalt ferrite (CoFe 2 O 4 ), and poly(vinylidene fluoride) (PVDF) is achieved by the polymerization technique. A nanocomposite consisting of polyaniline (PANI) and CoFe 2 O 4 is prepared using the interfacial chemical oxidation polymerization technique, resulting in a composition containing 50 wt.% of CoFe 2 O 4 . Nanoparticles of cobalt ferrite (CoFe 2 O 4 ) were synthesized by using the sol–gel auto-combustion process. The PANI/CoFe 2 O 4 (1:1) nanocomposites with weight percentages of 5, 10, 15, and 20 are incorporated into the PVDF matrix as fillers in order to alter the morphology and AC electrical conductivity of the PVDF/PANI/CoFe 2 O 4 composite materials. The structural and morphological properties were studied using characterization techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. At room temperature, impedance spectroscopy, dielectric measurements, and AC electrical conductivity were carried out in the frequency range of 40 Hz to 5 MHz. The dielectric permittivity has been shown to decline exponentially in low-frequency zones before remaining almost constant up to 5 MHz. When the frequency is increased up to 1 MHz, the AC conductivity of all composites remains constant; after that, it increases as the frequency increases. It was found that PANI-CoFe 2 O 4 nanocomposites modified the overall charge transport mechanism by modulating the core grain and grain boundary. The experimental Nyquist plot for different composite samples was fitted by an appropriate RC electrical model to evaluate relaxation time. The relaxation time τ 1 ( R 1 C 1 ) and τ 2 ( R 2 C 2 ) were both reduced after the reinforcement of PANI-CoFe 2 O 4 nanocomposites.