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.