studies on electrical and sensing properties of polyaniline / iron oxide (-fe2o3) nanocomposites

M. V. N.Ambika Prasad et al Int. Journal of Engineering Research and Applications www.ijera.com

ISSN : 2248-9622, Vol. 4, Issue 9( Version 1), September 2014, pp.198-202

www.ijera.com 198 | P a g e

Studies on Electrical and Sensing Properties of Polyaniline / Iron

Oxide (-Fe2O3) Nanocomposites.

Jakeer Husain1, Chakradhar Sridhar B

2, M. V. N.Ambika Prasad

1*

1Department of Materials Science Gulbarga University Gulbarga.585106 Karnataka, India.

2Department of Physics Gulbarga University Gulbarga.585106 Karnataka, India.

1*Department of Materials Science Gulbarga University Gulbarga.585106 Karnataka

ABSTRACT Polyaniline iron oxide nanocomposites were prepared by in-situ polymerization method. These

nanocomposites were characterized by employing Fourier Transform Infrared (FT-IR), 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 of its ease

preparation, good environmental stability, better

electronic properties, low cost, density is very low

and its applications in electrochromic display, electro

catalysis, rechargeable batteries, sensors and

biosensors [5-14].Polymer nanocompositesare also

known as nanostructure materials because of 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

acid in distilled water. This solution stirred for ½

hour on magnetic stirrer. Yellow precipitate of iron

oxalate dehydrate 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,

then 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 these

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

RESEARCH ARTICLE OPEN ACCESS




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

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 FT-IR ANALYSIS

40

4.6

942

2.8

443

2.8

344

5.6

146

1.0

7

47

0.9

4

47

6.3

8

48

2.8

9

49

0.5

2

51

4.3

7

52

5.6

2

53

7.7

7

55

3.7

6

56

9.2

9

58

8.3

2

59

5.1

6

61

0.7

1 61

9.2

0

62

9.9

9

63

9.4

3

66

2.2

3

10

10

.23

10

83

.06

11

88

.63

15

08

.27

15

41

.45

15

60

.45

16

37

.50

16

54

.56

34

31

.41

36

76

.65

37

37

.94

-10

0

10

20

30

40

50

60

70

80

90

100

%T

500 1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-1) Fig (a)pure iron oxide.

41

3.4

441

9.7

942

9.9

444

7.3

545

3.2

745

9.1

5

46

4.2

0

48

0.9

5

49

1.9

7

50

4.5

3

51

1.3

2

52

5.0

9

54

0.7

7

55

7.8

056

8.2

6

58

0.7

9

58

7.4

5

59

6.3

7

61

7.2

3

63

6.5

565

4.2

3

66

7.5

7

67

6.8

3

69

4.3

6

70

1.6

7

71

8.4

274

1.1

8

75

0.7

9

79

6.1

0

81

3.5

3

84

5.2

5

85

5.7

0

88

0.4

1

98

3.8

5

11

05

.35

13

01

.59

14

51

.23

14

74

.90 15

40

.80

15

60

.98

16

84

.14

17

93

.28

23

32

.12

23

65

.70

29

33

.71

34

34

.28

34

89

.22

35

08

.68

35

77

.18

36

16

.47

36

29

.32

36

76

.32

37

45

.49

37

73

.51

37

85

.37

38

22

.31

38

39

.23

38

53

.02

38

78

.66

-20

-10

0

10

20

30

40

50

60

70

80

90

%T

500 1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-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 stretch because of absorption of water molecules,

the characteristic stretching frequencies at 1654 cm-1

is due to N-H stretch, the peaks at 1083 to 1010 cm-1

is due to C-H bending the peaks from 657 to 424 cm-

1is due to metallic stretch.

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 stretching ,the peaks at 2933 to 2332 cm-1

is

due to C-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 cm-1

is due to metallic stretch .By comparing IR

spectra 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 attribute due to Vander

walls kinds 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 cluster of spherical shaped particles. figure 4.

2.(b) Shows the micrograph of iron oxide

nanocomposite it is observed that the iron oxide

nanocomposites 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.




4.3 Thermal analysis

0 100 200 300 400 500 600 700 800 900

90

92

94

96

98

100

Weig

ht

loss

Temprature

Pani/iron oxide nanocomposites

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 the 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.

40 60 80 100 120 140 160 180 200

5.0x10-6

1.0x10-5

1.5x10-5

2.0x10-5

2.5x10-5

d

c(S/c

m)

Temprature (oC)

Pani

10wt%

20wt%

30wt%

40wt%

50wt%

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 180 0c. 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

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,

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

T0.

4.5 Sensing studies




-200 0 200 400 600 800 1000 1200 1400 1600 1800 2000

0.0

5.0x102

1.0x103

1.5x103

2.0x103

2.5x103

3.0x103

3.5x103

Sen

siti

vit

y%

Time in seconds

pani

10wt%

20wt%

30wt%

40wt%

50wt%

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 height sensitivity this

is 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 are

V. CONCLUSIONS: Polyaniline Iron oxide nanocomposites were prepared

by in-situ polymerization method, the FT-IR spectra

conforms 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 on electrical and Sensing

parameter such as conductivity and Sensitivity of

these nanocomposites. The DC conductivity studied

shows the prepared nanocomposites exhibits typical

semiconductor behavior. It is conclude 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.

REFERENCES

[1]. P. Tartaj, MD Morales, Veintemillas-

Verdaguer S, Gonzalez-CarrenoTand

Serna C.J.J Phys D36:. 2003 .182–197.

[2]. C Sun, JSH Lee and M Zhang, Adv Drug

Deliv 2008 .1252–1265.

[3]. P Li, DE Miser, S Rabiei, RT Yadav and

MR Hajaligol, Appl Catal B43: 2003.151–

162.

[4]. S Sun, CB Murray, D Weller, L Folks and A

Moser,. 20001989–1992.

[5]. R. L. N Chandrakanthi,.;,M. A Careem.Thin

Solid Films., 2002 .51-56..

[6]. P. R Somani,. R Marimuthu,. Up Mulik,. . S.

R Mulik,.; S. R Sanikar,. D Amalnerkar,.

P.J.Synth.Met 1999. 45-52.

[7]. Y. He.J.Mater. Chem. Phys 2005.pp 134-

137.

[8]. L Geng.; Y Zhao,.; X Huang,.; S Wang,.;

S.Zhang,; and J. Wu,S. Sens and Actuat

2007 568–572.

[9]. S Yu,. M Xi,. X Jin,.; K Han,.; Z Wang,.;

and H Zhu,. J.Catalysis Communications.

2010 1125-1128.

[10]. C. C Buron,. B Lakard,. A .FMonnin,. . V

Moutarlier,. and S Lakard,. J.Synth Met.,

2011 ,2162-2169.

[11]. B. Adhikari, S. Majumdar, Prog. Polym.Sci.

2004 679.

[12]. D. T. McQuade, A. E. Pullen, T. M. Swager,

Chem. Rev. 2000.

[13]. M. Gerard, A. Chaubey, B. D.

Malhotra Biosensors Bioelectronics2002.

345 .

[14]. J. P. Chiang, A. G. MacDiarmid, Synth.

Met.1986. 193.

[15]. R. Sinha. Outlines of polymer technology

(New Delhi: Prentice Hall of India Private

Limited) 2002.

[16]. C.Laberty, P. Alphonse, J. J. Demai, C.

Sarada, A.Rousset, Materials ReseaBulletin

.1997.249 .