M. V. N.Ambika Prasad et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 9( Version 1), September 2014, pp.198-202
RESEARCH ARTICLE
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OPEN ACCESS
Studies on Electrical and Sensing Properties of Polyaniline / Iron
Oxide (Γ-Fe2O3) Nanocomposites.
Jakeer Husain1, Chakradhar Sridhar B2, M. V. N.Ambika Prasad1*
1
Department of Materials Science Gulbarga University Gulbarga.585106 Karnataka, India.
Department of Physics Gulbarga University Gulbarga.585106 Karnataka, India.
1*
Department of Materials Science Gulbarga University Gulbarga.585106 Karnataka
2
ABSTRACT
Polyaniline iron oxide nanocomposites were prepared by in-situ polymerization method These nanocomposites
were characterized by employing Fourier Transform Infrared (FTIR), Scanning Electron Microscope
(SEM),Thermal study by (TGA).The dc conductivity of prepared nanocomposites was measured as a function of
temperature which shows the strong interaction between Polyaniline and iron oxide nanoparticles and exhibits
semiconducting behavior.Finally, the sensing properties of these nanocomposites are also studied at room
temperature.
Keywords: Nanocomposites, FTIR, TGA, SEM, Conductivity,
I. INTRODUCTION
Conducting Polymer inorganic nanocomposites
attracted both fundamental and practical interest
because of their different chemical, biological and
physical properties and application in high density
magnetic recording,catalysis, magnetic resonance
imaging, energy conversion etc.[1-4]. Among all
conducting polymer Polyaniline is one of the most
promising conducting polymers due to its ease
preparation, good environmental stability, better
electronic properties, low cost, low density and its
applications in electrochromic display, electro
catalysis, rechargeable batteries, sensors and
biosensors [5-14]. Polymer nanocomposites are also
known as nanostructure materials because it improve
the performance properties of the polymer by doping
inorganic nanoparticles[15].Among all metal oxide
nanoparticles,
iron
oxides
have attracted
technological importance and potential applications
in catalysis such as magnetic storage devices,
ferrofluids and other uses [16-17]. In the present
work, the Polyaniline nanocomposites were
synthesized by in-situ polymerization method, the
synthesized nanocomposite were characterized by
FT-IR,SEM, Thermal Studies like TGA and also we
study the DC-conductivity and sensing properties of
these prepared nanocomposites.
II. EXPERIMENTAL
2.1 SYNTHESIS OF IRON OXIDE
NANOPARTICLES.
The iron oxide nanoparticles were synthesized
by self-propagating low temperature combustion
method, employing iron oxalate as precursor. The
Precursor is prepared by dissolving equimolar
quantity of ferrous ammonium sulphate and oxalic
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acid in distilled water. This solution stirred for ½
hour on magnetic stirrer. Yellow precipitate of iron
oxalate hydrate obtained is filtered and washed with
distilled water. The prepared iron Oxalate was mixed
with Polyethylene glycol (PEG) in the weight ratio
1:5. The resultant compound was placed in a crucible
and heated by using electrical heater. It was observed
that initially PEG is melted, then frothed and finally
ignited to give iron oxide as a residue, the prepared
compound was then calcinated for 2 hours to remove
impurities. Finally pure iron oxide nanoparticles were
obtained.
2.1 PREPARATION OF PANI/IRON OXIDE
NANOCOMPOSITES.
Synthesis of the PANI– iron oxide
nanocomposites was carried out by in-situ
polymerization method. Aniline (0.1 M) was mixed
in 1 M HCl and stirred for 15 min to form aniline
hydrochloride. Iron oxide nanoparticles were added
in the mass fraction to the above solution with
vigorous stirring in order to keep the iron oxide
homogeneously suspended in the solution. To this
solution , 0.1 M of ammonium persulphate, which
acts as an oxidizer was slowly added drop-wise with
◦
continuous stirring at 5 C for 4 h to completely
polymerize. The precipitate was filtered, washed with
deionized water, acetone, and finally dried in an oven
for 24 h to achieve a constant mass. In this way,
PANI– iron oxide nanocomposites containing various
weight percentage of iron oxide (10 %, 20 %, 30 %,
40 %, and 50 %) in PANI were synthesized.
III. CHARACTERIZATION.
Fourier transformed infrared spectra of these
nanocomposite were recorded on Thermo Fisher
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M. V. N.Ambika Prasad et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 9( Version 1), September 2014, pp.198-202
ATR Nicolet model using diamond (iS5) in the range
4000-400cm-1. The morphology of the nano iron
oxide and nanocomposites in the form of powder was
investigated using SEM Model-EVO-18 Special
Edison, Zein Germany. Thermal studies were carried
out employing STA PT1600 Thermal Analyzer from
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Linseis under nitrogen atmosphere with a heating rate
of 10oC/minute at a flow rate of 100 ml/min.
Electrical properties of these nanocomposites are
studied by using Keithley 6514 electrometer and
sensing properties of these nanocomposites were
studied using laboratory set up.
IV. RESULT AND DISCUSSION
4.1 FTIR ANALYSIS
100
90
80
70
60
%T
50
40
0
34 31.41
37 37.94
36 76.65
10
66 2.23
63 9.43
62 9.99
61 0.71
11 88.63
59 5.16
58 8.32
10 83.06
56 9.29
10 10.23
55 3.76
53 7.77
52 5.62
49 0.52
48 2.89 61 9.20
47 6.38
47 0.94 51 4.37
46 1.07
44 5.61
43 2.83
42 2.84
40 4.69
16 54.56
16 37.50
20
15 60.45
15 41.45
15 08.27
30
- 10
400 0
350 0
300 0
250 0
200 0
150 0
100 0
500
W av enu mber s ( c m- 1)
Fig (a)pure iron oxide.
90
80
70
60
50
23 65.70
23 32.12
29 33.71
10
53.02
85.37
39.23
78.66
73.51
38
37
38
3722.31
37 45.49
36 76.32
36 29.32
36 16.47
35 77.18
35 08.68
34 89.22
34 34.28
20
46 4.20 56 8.26
55 7.80
45 9.15 45 3.27
44 7.35
42 9.94
41 9.7941 3.44
15 60.98
17 93.28
14 74.90
14 51.2316 84.14
30
88 0.41
85 5.70 15 40.80
84 5.25 13 01.59
79 6.10
11 05.35
75 0.79
66 7.57
61 7.23
70 1.67
59 6.37
69 4.36
58 7.45
67 6.83
58 0.79
54 0.7798 3.85
52 5.09
51 1.32
81 3.53
50 4.53
74 1.18
71 8.42
49 1.97
48 0.9565 4.23
63 6.55
%T
40
0
- 10
- 20
400 0
350 0
300 0
250 0
200 0
150 0
100 0
500
W av enu mber s ( c m- 1)
Fig (b)pani/iron oxide nanocomposite..
Fig.4.1 (a) & (b) shows the FTIR spectra iron oxide and pani/iron oxide nannocomposites.
Fig 4.1(a) shows FTIR spectra of pure iron oxide
nanoparticles the peaks at 3737 to 3431 cm-1 is due to
-OH stretching because of absorption of water
molecules, the characteristic stretching frequencies at
1654 cm-1 is due to -N-H stretching, the peaks at
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1083 to 1010 cm-1 is due to -C-H bending the peaks
from 657 to 424 cm-1is due to metallic stretching.
Fig 4.1(b) shows the IR spectra of Pani/iron oxide
nanocomposite the characteristic stretching frequency
was observed at 3745 to 3434 cm-1 is due to -O-H
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M. V. N.Ambika Prasad et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 9( Version 1), September 2014, pp.198-202
stretching ,the peaks at 2933 to 2332 cm-1 is due toC-H stretch, the peaks at 1793 and 1684 cm-1 is due
to C=O stretch ,the peaks 1560 to 1451 cm-1 is due to
-C-H bending ,the peaks at 880 to 676cm-1 is due to
Alkene=C-H bending and the peaks at 540 to 429 cm1
is due to metallic stretch .By comparing IR spectra
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of pani and pani/iron oxide nanocomposite, it is
observed that in the composite the characteristic
stretching frequencies are shifted towards higher
frequencies side which may be due to Vander walls
kind of interaction between iron oxide and pani
chain.
4.2 SCANNING ELECTRON MICROSCOPY
Fig (a)Pure Iron oxide
Fig (b)Pani/iron oxide nanocomposite.
Figure 4.2 Scanning electronic micrograph (SEM) image of Pure Iron oxide and Pani/Iron oxide nanocomposite.
Figure 4.2(a) & (b) shows the micrograph of iron
oxide and Pani/Iron oxide nanocomposites. It is seen
clearly from the SEM micrograph of iron oxide, it
has a cluster spherical shaped particles. Figure 4.
2.(b) Shows the micrograph of iron oxide
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nanocomposite it is observed that the iron oxide
nanocomposite are cluster like structure. The
presence of such sharp crystal of iron oxide
nanoparticles has a strong influence on various
electrical parameters of these nanocomposites.
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M. V. N.Ambika Prasad et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 9( Version 1), September 2014, pp.198-202
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4.3 Thermal analysis
100
Pani/iron oxide nanocomposites
Weight loss
98
96
94
92
90
0
100
200
300
400
500
600
700
800
900
Temprature
Figure 4.3 shows the TGA graph of 50wt% Pani/Iron oxide nanocomposite
Figure 3 shows the thermo graph of Pani/Iron
oxide nanocomposites. the thermograph shows two
weight losses as seen in fig 3. The first weight loss
corresponds to evaporation of water molecules from
the prepared nanocomposites.The second weight loss
is due to the decomposition of organic moiety.
4.4 DC CONDUCTIVITY STUDIES.
-5
2.5x10
Pani
10wt%
20wt%
30wt%
40wt%
50wt%
-5
2.0x10
-5
dc(S/cm)
1.5x10
-5
1.0x10
-6
5.0x10
40
60
80
100
120
140
160
180
200
o
Temprature ( C)
Fig.4 shows the dc conductivity of pani/iron oxide nanocomposites..
Fig 4 shows the DC conductivity of Polyaniline
and Pani/iron oxide nanocomposite of different
weight percentage as a function of temperature range
from 30 to 1800c. The DC conductivity remains
almost constant up to 1200c and thereafter it increases
up to1800c, which is the characteristic behavior of
semiconducting materials. The conductivity increases
with an increase in temperatures due to the flow of
ions from one localized state to another and it is also
suggested here that the thermal curling effects of the
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chain alignment of the Polyaniline leads to the
increase in conjugation length and that brings about
the increase of conductivity.
The conductivity varies directly with the
temperature obeying an expression of the following
form:
σ (T) = σ0exp [-T0/T)1/4]
Where: σ is the conductivity, T is the temperature and
σ0 is the conductivity at characteristic temperature T 0.
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M. V. N.Ambika Prasad et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 9( Version 1), September 2014, pp.198-202
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4.5 Sensing studies
3
3.5x10
3
3.0x10
3
2.5x10
Sensitivity%
3
2.0x10
3
1.5x10
pani
10wt%
20wt%
30wt%
40wt%
50wt%
3
1.0x10
2
5.0x10
0.0
-200
0
200
400
600
800
1000 1200 1400 1600 1800 2000
Time in seconds
Fig.5. Variation of sensitivity against LPG
Fig (5). Shows sensitivity vs time for Polyaniline
/Iron oxide nanocomposites it is seen that the
Pani/iron oxide nanocomposites shows better
sensitivity to gas vapor. Compared to pure
Polyaniline and other
nanocomposites such as
(10,20,30,40 wt%) 50wt% nanocomposites shows
high sensitivity due to the strong interaction between
the Polyaniline and iron oxide nanoparticles. In the
case of pure Polyaniline and 10wt% of
nanocomposites sensitivity is very low because of
lower surface area.
V. CONCLUSIONS:
Polyaniline Iron oxide nanocomposites were prepared
by in-situ polymerization method, the FTIR spectra
confirms the formation of pani/iron oxide
nanocomposites. The SEM image shows the presence
of iron oxide nanoparticles which are uniformly
distributed throughout the nanocomposite sample.
The presence of iron oxide nanoparticle in Pani
nanocomposites influences the electrical and Sensing
parameter such as conductivity and sensitivity of
these nanocomposites. The DC conductivity studies
show the prepared nanocomposites exhibits typical
semiconductor behavior. It is concluded that this Pani
iron oxide nanocomposites is one of the promising
materials for the potential applications.
VI ACKNOWLEDGEMENTS:
The
author
Jakeer
Husain
gratefully
acknowledges the financial support from DST
INSPIRE Program.
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