Electromagnetic properties of polyaniline/maghemite nanocomposites: I. The
effect of re-doping time on the electromagnetic properties
Abstract
This
article is
to carry
out researches
on the synthesis
of the polyaniline/ γ
-Fe2O3 nanocomposites by a reverse micelle process and the effects of re-doping time on the
electromagnetic properties of polyaniline/γ-Fe2O3 nanocomposites, investigated by Fourier
transform spectrometer (FT-IR), X-ray photoelectron spectroscopy (XPS), wide angle X-ray
diffraction diffractometer (WAXD), impedance analyzer, micro-ohmeter, and superconductor
quantum
interference
device
(SQUID).
The
nanostructure
of
the
polyaniline/ γ
-Fe2O3 nanocomposites was characterized by micrographs of transmission electron
microscopy (TEM). It was found that the dispersed γ-Fe2O3 phase is roughly distributed in the
polyaniline matrix. Results showed that, in the presence of γ-Fe2O3, the growth rate of quinoid
ring is markedly retarded. The crystallinity and doping level of polyaniline in the
nanocomposites increase with re-doping time, the conductivity and dielectric properties (i.e.,
permittivity and loss factor) of nanocomposites are hence increased and the ionic polarization
relaxation time become shorter from 1.71 × 10−9 to 7.48 × 10−10 s. The particle size and γ
-Fe2O3 content in the nanocomposites decrease with re-doping time due to the reduction effect
resulting from the doped protonic acid of polyaniline. For the room-temperature SQUID
analysis, the superparamagnetic behavior is observed, suggesting the presence of the thermal
activation energy contribution to the magnetic moment. The saturated magnetization was
decreased with decreasing γ-Fe2O3 contents.
Keywords

Polyaniline/γ-Fe2O3 nanocomposites;

Reverse micelle;

Electromagnetic properties;

Dielectric properties;

Superparamagnetic behavior