Thermal, dielectric and microwave absorption properties of polyaniline-CoFe2O4 nanocomposites

The present paper deals with the synthesis of conducting ferromagnetic polyaniline-CoFe2O4 (PC) nanocomposites via one-step chemical oxidative polymerization of aniline in the presence of CoFe2O4 nanoparticles (30-40 nm). These nanocomposites of PC have been characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). Extended thermal analysis has revealed that the activation energy of these nanocomposites varies from 75.3 to 84.3 kJ/mol as compared to the activation energy of 50.3 kJ/mol for polyaniline-DBSA. In addition, dielectric and microwave absorption properties of the nanocomposites have been measured in the frequency range of 12.4-18 GHz (Ku-band) which demonstrate that more than 99% attenuation of microwaves (SEA = 21.5 dB) has been achieved using these nanocomposites. Systematic investigations reveal that the CoFe2O4 nanoparticles in the polyaniline matrix have phenomenal effect in determining the microwave absorption properties of the nanocomposites. (C) 2011 Elsevier Ltd. All rights reserved.