JOURNAL OF MATERIALS SCIENCE 40 (2 005) 3013 – 3015 L E T T E R S
Synthesis and characterization of γ-Fe
2
O
3
—polythiophenen
nanocomposites
HUA-RU YIN, JI-SEN JIANG
∗
Department of Physics and Chemistry, Center for Functional Nanomaterials and Devices,
East China Normal University, Shanghai 200062, People’s Republic of China
E-mail: jsjiang@phy.ecnu.edu.cn
Recently, inorganic/conducting polymer composites
with good electrical and magnetic properties have
received tremendous attention, and study on this kind
of composites has become one of the most active
and promising research fields. What makes inor-
ganic/conducting polymer composites so attractive is
their potential application to batteries, electro-chemical
display devices, molecular electronics, electro-
magnetic shields, and microwave-absorbing materials
etc. [1, 2]. Until now, the research on this aspect is
mainly limited to magnetic polypyrrole nanocompos-
ites [3–5] and magnetic polyaniline nanocomposites
[6, 7]. Polythiophene and its derivatives are research
hotspots in the conducting polymer area for their easy
polymerization and stabilization in air. Chen [8] and
Faid [9] et al. have doped polythiophene and its deriva-
tives with I
2
and BF
−
4
to improve their conductivity.
However little research on magnetic polythiophene
(PTP) nanocomposites is reported. In this letter, we re-
port a novel chemical synthesis of a γ -Fe
2
O
3
encapsu-
lated PTP (γ -Fe
2
O
3
-PTP) conducting nanocomposite.
γ -Fe
2
O
3
nanoparticles were synthesized according
to the following procedure: a solution of FeCl
3
·6H
2
O
and FeSO
4
·7H
2
Owas mixed and stirred at room
temperature. Then NaOH solution was added to the
mixed solution until the pH values of the reaction
mixture reached the range of 13–14. The resulting
nanoparticles were put into an oven at 80
◦
C for 3 hrs,
then filtered, washed and dried in air. γ -Fe
2
O
3
nanopar-
ticles prepared from the previous step were modified
by polyethylene glycol (PEG-400), then added into
a round-bottom flask equipped with a mechanical
stirrer. CHCl
3
and thiophene monomer were added to
the flask. Then anhydrous ferric chloride was added
and stirred at 0
◦
C for 2 hrs. After the ice bath was
removed, the mixture was allowed to warm to room
temperature and to stir for 3 hrs. CHCl
3
was evaporated
and the residue was added to 1 M HCl (0
◦
C). The
product was filtered, washed and dried in vacuum. Pure
polythiophene was prepared with a similar method
as the preparation of γ -Fe
2
O
3
-PTP, but γ -Fe
2
O
3
nanoparticles and PEG-400 were not required.
The phase composition of γ -Fe
2
O
3
-PTP nanocom-
posites were characterized by X-ray diffraction (XRD)
using a D8 ADVANCE diffractometer employing Cu
∗
Author to whom all correspondence should be addressed.
K
α
(λ = 0.154 nm) radiation. The structure of the sam-
ples was analyzed by FTIR PE580-B using samples
pressed into pellets with KBr. The morphologies of
the γ -Fe
2
O
3
-PTP nanocomposites were observed
using TEM JEM-100CX. The microstructure of the
samples was investigated by M¨ossbauer spectroscopy
using a constant—acceleration spectrometer with a
57
Co source in a Pd matrix at room temperature.
Hyperfine interaction parameters were derived from
the M¨ossbauer spectra using a least-squares method.
The spectrometer was calibrated using a standard
25 µm α-Fe foil.
The TEM photograph of γ -Fe
2
O
3
in Fig. 1a shows
an average particle size of 10–20 nm. The TEM pho-
tograph of γ -Fe
2
O
3
-PTP in Fig. 1b shows that the
γ -Fe
2
O
3
nanoparticles are encapsulated by polythio-
phene successfully.
In the stretching vibration region, for thiophene
monomer there are two peaks centered at 3060 and
3100 cm
−1
due to aromatic C
α
-H and C
β
-H stretch-
ing vibration. However, for polythiophene there is only
one broad peak centered at about 3060 cm
−1
in pro-
portion to the thiophene ring at the end of the poly-
mer, which is very small [10]. Figs 2a and b are the
FTIR spectra of PTP and γ -Fe
2
O
3
—PTP. As can be
seen, in both Figs 2a and b, only one broad peak is
present at 3060 cm
−1
.Inthe fingerprint region, the ab-
sorption peak at 790 cm
−1
is due to the out-of-plane
vibration of the 2,5-substituted thiophene ring created
by the polymerization of thiophene monomer. This may
prove that thiophene monomer has polymerized in both
cases. The peak centered at 1655 cm
−1
in Fig. 2a is
usually ascribed to the vibration of C
O group, sug-
gesting the possibility of polythiophene reacting with
O
2
, this result is in accordance with the literature [11].
When encapsulating γ -Fe
2
O
3
nanoparticles, this peak
moves to 1633 cm
−1
, which proves that interaction hap-
pens between C
O and γ -Fe
2
O
3
nanoparticles. The
absorption peak at 698 cm
−1
was due to the thiophene
ring breathing vibration. After encapsulating γ -Fe
2
O
3
nanoparticles this peak is weakened apparently and
moves to low wavenumber, indicating that γ -Fe
2
O
3
has
an effect on the thiophene ring. The peak in Fig. 2b at
580 cm
−1
indicates the presence of γ -Fe
2
O
3
nanoparti-
cles [12]. All this proves that strong interaction happens
0022–2461
C
2005 Springer Science + Business Media, Inc.
3013