Adsorption
of Charge Carriers on Radial Zinc Oxide
and the Study of Their Stability and Dielectric Behavior in Poly(vinylidene
fluoride)
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Abstract
Radial zinc oxide (ZnO) was prepared
using a new user-friendly
chemical process, and the surface was modified by adsorbing polyaniline
(PANI) as a charge carrier. The modified ZnO (PZnO) was used to prepare
poly(vinylidene fluoride) (PVDF)–PZnO nanocomposites with improved
dielectric properties. The structural morphology of the fillers was
examined using powder X-ray diffraction and then correlated with observations
from high-resolution transmission electron microscopy. A new characterization
technique was used to study the maximum adsorption limit by performing
solvent relaxation nuclear magnetic resonance experiments, and the
results suggested that a maximum of 10% PANI is adsorbed onto the
ZnO. The adsorbed PANI acted as an interface and stabilized the ZnO
in PVDF solution due to strong interactions between the matrix and
fillers. An electron spin resonance (ESR) study was carried out to
characterize the spin resonance of ZnO and PZnO. The adsorption of
PANI onto ZnO generated charge carriers, and hence, under the influence
of a magnetic field, the samples exhibited dissimilar resonance behavior.
Dielectric studies of the PVDF–PZnO composites were performed,
and the PVDF–ZnO composites and pure PVDF were compared over
a wide range of frequencies (0.01 Hz–1 MHz) and temperatures
(25–90 °C). The results suggest that the PVDF–7.5PZnO
composite showed a significantly improved dielectric constant with
a decrease in dielectric loss (0.2), most likely because the adsorption
of PANI onto ZnO led to strong interactions between the matrix and
fillers and enhanced the interfacial polarization in PVDF