Dielectric properties of polyaniline-montmorillonite clay hybrids

Polyaniline (PANI)-montmorillonite clay (MMT) hybrid (PANI-MMT) was prepared by mechanical grinding of ANI and MMT in the presence of potassium perdisulphate (KPS) followed by soaking the mass in 0.1 (M) HCl for 24 h. The formation of PANI-MMT hybrid was confirmed by Fourier transform infrared spectroscopic analyses. XRD studies revealed the intercalation of PANI into twodimensional silicate galleries of MMT. HRTEM analyses indicated particle size distribution to be in the range of 40-55 nm. The real part of the dielectric constant reached values as high as 4500 at frequency ∼10² Hz for a MMT:PANI = 1:1 weight ratio, the value decreasing with increasing frequency up to 25 kHz, and also with increasing MMT loading in the hybrids. This dispersion was indicative of the interfacial space charge polarization (Maxwell Wagner type). Grain boundary resistance and capacitance of the hybrid along with the conductivity-relaxation time for the hybrid at several PANI:MMT weight ratios were evaluated from the complex impedance plot considering the Maxwell-Wagner Two-Layered Model AC conductivity was independent of frequency in the range 0.1-1 kHz and thereafter found to rise in the range 1-25 kHz due to trapped charges. DC conductivity values of the hybrids were lower than the PANI homopolymer.