Inorganic nanoparticles of different nature and size can be combined with the conducting
polymers, giving rise to a host of nanocomposites with interesting physical properties and
important application potential. Such nanocomposites have been discussed in this review,
throwing light on their synthesis techniques, properties, and applications. A large variety
of nanoparticles have been chosen in this respect with inclusion techniques utilizing both
chemical and electrochemical routes. The nature of the association between the components
can be studied from TEM pictures. Depending upon the synthesis techniques and the
characteristics of the inorganic materials, ultimate properties of the resulting composite
are controlled. In this way, the exceptional colloidal stability of different silica sols have
been utilized to form stable PPy-silica and PAn-silica nanocomposite colloids. Similarly the
magnetic susceptibility of γ-Fe2O3, the elctrochromic property of WO3, and the catalytic
activity of Pd, Pt, etc. metals have been successfully combined with existing electrical
conductivity of conducting polymers in the hybrid nanocomposite materials. Functional
groups viz. −NH2 and −COOH have also been added to the composite particles and all these
combinations and modifications have improved the applicability of conducting polymers in
different fields, e.g., electrodes of batteries, display devices, immunodiagnostic assay, etc.
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.
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