Characterization and dielectric properties of polyaniline-TiO2 nanocomposites

Nanocomposites of polyaniline (PANI)-titanium dioxide (PANI-TiO2) are prepared from a colloidal sol of TiO2 nanoparticles. The dc and ac conductivities of samples with different concentrations of PANI have been investigated as a function of frequency and temperature. The dc conductivity follows three-dimensional variable range hopping. The ac conductivity has been interpreted as a power law of frequency. The temperature variation of the frequency exponent suggests a correlated barrier hopping conduction process in the nanocomposites. A very large dielectric constant of about 3700 at room temperature has been observed. An electric modulus presentation is used to interpret the dielectric spectra. The interface between polyaniline and TiO2 plays an important role in yielding a large dielectric constant in the nanocomposite.