World Journal of Engineering
ELECTROMAGNETIC PROPERTY OF POLYANILINE WITH DIFFERENT
NANOSTRUCTURES DOPED WITH D-CSA
1
Shibu Zhu, Xiangnan Chen, Zuowan Zhou
Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and
Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
Characterization
The morphologies of resulting polyaniline were
Introduction
observed on an environmental scanning electron
Conducting polymers are a new microwave absorbents,
microscopy (SEM, American Fei Quanta 2000) and a
which exhibit a lot of advantages over traditional
transition electron microscopy (TEM, Hitachi H-700H ).
inorganic absorption materials such as low density,
Fourier transform infrared (FTIR) spectra (KBr
easily complexing and processing and adjustable
dispersed pellets) in the range 400–4000 cm-1 were
electromagnetic parameters by controlling doping
recorded on a fully computerized Nicolet 5700
degree, dopant and main polymer chain [1]. Compared
spectrometer at a resolution of 4 cm-1. The permittivity
with other conducting polymers, polyaniline (PANI)
(  ' ,  ' ' ) and permeability (  ' ,  ' ' ) of the samples were
stands out because of its many outstanding properties,
measured by a reflection/transmission technology using
including
remarkable
processability,
good
an AV3618 network analyzer in the frequency range of
environmental stability, wide-range and controllable
2–18 GHz.
conductivity and ease of synthesis [2, 3]. Many
Results and discussion
morphologies of PANI have been successfully
synthesized. It is of great interest to study the
electromagnetic properties of PANI with different
nanostructured morthologies. In this work, we prepared
PANI nanotube, nanofiber and nanograin doped with
CSA and studied their electromagnetic properties.
Figure 1 SEM images of polyaniline doped with different molar
Experimental
ratios of [CSA]/[Ani] at (a) 1:1, (b)1:4 and (c) 1:8.
Materials
The monomer of aniline was distilled under reduced
Figure 1 gives the SEM images of PANI doped with
different molar ratios of [CSA]/[Ani] and the insert
figures are the TEM images of correlated morphologies.
It was found that the molar ratios of [CSA]/[Ani]
greatly affected the morphologies and size of resulting
PANI, which depended on the structure of micelles
consisting of CSA and aniline [5]. For instance, we
could obtain PANI nanotubes with rectangular cross
section when the molar ratio of [CSA]/[Ani] was 1:1,
while received PANI nanograins with the diameter of ca.
150 nm when the molar ratio of [CSA]/[Ani] reduced to
1:8. Thus, we can obtain PANI with different
morphologies by controlling the molar ratios of
[CSA]/[Ani] in the reaction system.
FTIR spectra were used to characterize the chemical
structure of the as-prepared PANIs. The FTIR spectra of
as-prepared PANI doped with D-CSA at different molar
ratio of [CSA]/[Ani] are shown in Figure 2. In all of the
pressure (35 mmHg, 85 ℃) and then stored below
0 ℃. Other chemical reagents were analytical grade,
and used as received without further purification. All
experiments were carried out with deionized water.
Polymerization
The synthesis of polyaniline doped with D-CSA by
in-situ polymerization was conducted in aqueous
solution with APS as oxidant. A typical process of
polyaniline doped with D-CSA could find in our
previous work [4]. In this study, we prepared
polyaniline with different morphologies by controlling
the molar ratio of [CSA]/[Ani] in the reaction system.
The resulting dark green precipitate was washed with
deionized water and ethanol several times. The product
was dried in vacuum oven at 60 ℃ for 24 h.
1
Author to whom correspondence should be addressed, E-mail: zwzhou@at-c.net
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World Journal of Engineering
samples, the characteristic vibrations of PANI such as
the C=C stretching vibration of the quinoid ring at
about 1580 cm-1 and that of the benzene ring at 1502
cm-1 [6], the stretching mode of C–N at 1306 cm-1 and
electronic-like absorption of N=Q=N (Q representing
the quinoid ring) at 1153 cm-1 [7], were obviously
observed. While the intensity of characteristic peak
around 1045 cm-1 attributed to absorption of –SO3H
group decreased with decreasing the molar ratios of
[CSA]/[Ani], indicating that the doped degree of PANI
reduced.
order of the polaron and charge carrier [9], which
shows paramagnetic behavior [10] caused by nanotube
and nanofiber morphology of PANI.
Conclusion
Polyanilines with different morphologies were
successfully synthesized by changing the molar ratio of
[CSA]/[Ani] via in situ polymerization. The dosage of
CSA greatly affected the morphologies and size of
resulting PANI. It has been demonstrated that an
unusual magnetic loss for PANI nanotube and nanofiber
were observed at f =12-18 GHz.
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conducting polymers (2nd edn)” Marcel Dekker. New
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[3] Anderson, M. R., Mattes, B. R., Reiss, H. and Kaner,
R. K. Conjugated Polymer Films for Gas Separations.
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M., Lu, J. and Hui D. Synthesis and mechanism of
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of
self-assembled
polyaniline
nanotubes doped with D-10-camphorsulfonic acid.
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of
Poly(acrylic
acid)-Doped
Polyaniline.
Macromolecules 28 (1995) 2858–2866.
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spectra of soluble polyaniline. Synth. Met. 24 (1988)
231–238.
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polyaniline as a new microwave absorbent materials.
Polym. Adv. Technol. 12 (2001) 651-657.
[9] Cao, Y., Smith, P. and Heeger, A. J. Spectroscopic
studies of polyaniline in solution and in spin-cast films.
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a
b
1580
1502
1306
1153
1045
822
702
514
transmmitance(%)
References
c
4000
3500
3000
2500
2000
1500
1000
500
Wavenumbers(cm )
-1
Figure 2 FTIR spectra of the PANI with different morphologies
(a) nanotube, (b) nanofiber and (c) nanograins.
Figure 3 The dependence of microwave frequency on electrical
loss (a) and magnetic loss (b) of obtained PANI
Microwave behavior of conducting polymer critically
depends on dielectric and magnetic properties of
materials. The dependence of microwave frequency on
electrical loss and magnetic loss of obtained PANI are
shown in Figure 3. As one can see, all of the samples
exhibit electrical loss at the frequency of 2-18 GHz,
especially between 4-8 GHz. It has demonstrated that
PANI doped with HCl by conventional method only
displays electrical loss at microwave frequency [8].
However, the obtained PANI nanotube and nanofiber
display both electrical loss and magnetic loss at
microwave frequency, especially unusually high
magnetic loss at 10-18 GHz (as shown in figure 3),
while PANI nanograin exhibits no obvious magnetic
loss. PANI with morphologies of nanotube or nanofiber
show unusual magnetic loss probably arose from partial
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