Preparation of Polyaniline Nickel Oxide Nanocomposites and Evaluation of Its Electrical Properties

IJSTE - International Journal of Science Technology & Engineering | Volume 2 | Issue 08 | February 2016 ISSN (Online): 2349-784X

Preparation of Polyaniline/Nickel Oxide Nanocomposites and Evaluation of its Electrical Properties Jakeer Husain Associate Professor S&H, Farha Institute of Engineering, Chevella, JNTUH, Telangana, India

Narsappa Reddy Associate Professor ECM, JB Institute of Engineering & Technology, Moinabad, JNTUH, Telangana, India

Rahena Anjum Professor S&H, Farha Institute of Engineering, Chevella, JNTUH, Telangana, India

Syed Aslam Associate Professor Department of Mechanical Engineering Farha Institute of Engineering, Chevella, JNTUH, Telangana, India

Jai Sagar Assistant Professor Department of Mechanical Engineering Farha Institute of Engineering, Chevella, JNTUH, Telangana, India

Abstract NiO Nanoparticles (NNP) was synthesized by a self-propagating high temperature synthesis from nickel nitrate. Synthesized NiO are used to prepare Polyaniline (PANI)-NiO nanocomposites by in situ chemical oxidative polymerization at 0-50C. Different weight percentages of NiO (10%, 20%, 30% and 40%) were added during the polymerization. The nanocomposites were characterized by X-Ray diffraction (XRD).Surface morphology was studied using Scanning Electron Microscopy (SEM) and transmission Electron Microscopy (TEM). The dc conductivity of the samples was measured as a function of temperature in the range 30–1800C and it was found that the increasing the concentration of nanoparticles increases the conductivity and also the performance of a room temperature. These nanocomposites have microwave, sensor and battery applications.

Keywords: Polyaniline, Nanocomposites, XRD, SEM, DC conductivity ________________________________________________________________________________________________________ I.

INTRODUCTION

Composites containing inorganic particles have attracted great attention due to their different properties through doping, polyaniline is the most widely studied because of its ease to synthesis, low density, less cost, soluble in various solvents, good processibility and good conductivity[1].

The conducting polyaniline (PANI) is one of the promising conducting polymers due to its high conductivity, ease preparation, good environmental stability and large variety of applications [2-4] which make this polymer suitable for gas sensor [5], functional hybrid [6], as pH swchiting electrical conducting biopolymer hybrid for sensor applications [7], as an electrically active redox biomaterial for sensor applications [8], as a matrix for preparation of conducting polymer nanocomposites [9,10].

Therefore, there has been increasing interest of the researchers for the preparation of nanocomposites based on PANI. The literature review on conducting polymer nanocomposites show that PANI has been successfully utilized for the preparation of nanocomposites [11, 12]. When nanostructure filler particles are magnetic in polymer matrix, then such nanocomposites show enhance magnetic as well as transport properties of the polymer [13]. Recently, Karthik et al [16] have studied that the particle size has strong influence on the magnetic properties of NiO nanoparticles. Smaller particles have large interface area between the ferromagnetic phase and antiferromagnetic matrix and the structural disorder and exchange coupling increases with interface area. NiO is an antiferromagnetic transition metal oxide which is considered to be a semiconductor with p-type conductivity and band gap 3.51 eV [17]. NiO nanoparticles also have excellent thermal stability and capable of improving the thermal stability of PANI. Among these, combustion technique has received considerable attention, based on their interesting properties and applications. In the present paper, authors report the synthesis, characterizations, fabrication and effects of Nickel oxide nanoparticles in Polyaniline/ nanocomposites on Electrical properties.

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Preparation of Polyaniline/Nickel Oxide Nanocomposites and Evaluation of its Electrical Properties (IJSTE/ Volume 2 / Issue 08 / 010)

II. CHEMICAL SYNTHESIS OF POLYANILINE. The synthesis was based on mixing aqueous solution of aniline hydrochloride and ammonium persulphate at room temperature, followed by the separation of PANI hydrochloride precipitate by filtration and drying. Aniline hydrochloride (equi molar volume of aniline and hydrochloride acid) was dissolved in distilled water in a volumetric flask to 100 ml of solution.

Ammoniumpersulphate (0.25M) was dissolved in water also to 100ml of solution. Both solutions were kept for 1 hour at room temperature, then mixed in a beaker, stirred with a mechanical stirrer, and left at rest to polymerize. Next day, the PANI precipitate was collected on a filter, washed with 0.2 M HCL, and similarly with acetone. Polyaniline hydrochloride powder was dried in air and then in vacuum at 60oC for 24 hours. Polyaniline prepare under these reaction and processing conditions are further referred to as “standard” samples.

Synthesis Of Nickel Oxide Nanoparticles: The nickel oxide nanoparticles were synthesized by self-propagating low temperature combustion method, employing nickel oxalate as precursor. Precursor is prepared by dissolving equimolar quantity of Nickel chloride and oxalic acid in distilled water.

This solution is stirred for ½ hour on magnetic stirrer. Light green precipitate of nickel oxalate dehydrate so obtained is filtered and washed with distilled water. The prepared Nickel Oxalate was mixed with Polyethylene glycol (PEG) in the weight ratio 1:5.

The resultant compound was placed in a crucible and heated in air by using electrical heater and it was observed that initially PEG is melted, then frothed and finally ignited to give nickel oxide as a residue, then the prepared compound was then calcinated for 2 hours at 300 0C to remove impurities. Finally pure nickel oxide nanoparticles were obtained.

Synthesis Of Polyaniline/Nickel Oxide Nanocomposites: Synthesis of the Polyaniline– nickel 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. Nickel oxide nanoparticles were added in the mass fraction to the above solution with vigorous stirring in order to keep the nickel oxide homogeneously suspended in the solution.

To this solution, 0.1 M of ammoniumpersulphate, which acts as an oxidizer was slowly added drop-wise with continuous stirring at -5◦C for 4 hours 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, Polyaniline– Nickel oxidenanocomposites containing various weight percentage of Nickel oxide (10 %, 20 %, 30 %, 40 %, and 50 %)wt% in PANI were synthesized.

III. CHARACTERIZATION X-ray diffraction studies were performed using Philips X-ray diffractometer with CuK_ as the radiation source.. The morphology of the nanocomposites in the form of powder was investigated using scanning electron microscope (SEM) Model-EVO-18 (Special Edison, Zeiss, Germany). DC conductivity of these nanocomposites are studied by using Keithley 6514 electrometer.

IV. RESULT AND DISCUSSION XRD: 1400

200 1200

NiO

1000

Intensity

101 800

110

600

400

200

0 20

30

40

50

60

70

80

2 Theta

Fig. 4.1: shows the XRD pattern of Pure Nickel oxide nanoparticles

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Preparation of Polyaniline/Nickel Oxide Nanocomposites and Evaluation of its Electrical Properties (IJSTE/ Volume 2 / Issue 08 / 010)

The purity and crystallinity of the synthesized NiO nanoparticles were examined by using powder X-ray diffraction (XRD) as shown in Figure. It can be seen from Figure that the diffraction peaks are low and broad due to the small size effect and incomplete inner structure of the particle. All these diffraction peaks can be perfectly indexed to the face-centered cubic (FCC) crystalline structure of NiO, not only in peak position, but also in their relative intensity of the characteristic peaks, which is in accordance with that of the standard spectrum (JCPDS, No. 04-0835).The average particle size calculated by using Scherrer equation It is found that the particle size of nickel oxide is 20 nm.

SEM:

Fig. 4.2(a): shows the SEM image of Pure Nickel oxide nanoparticles

Fig. 4.2 (b) shows the SEM image of Polyaniline/NiO nanocomposite 50 wt%

figure 4.2 (a). It can be clearly seen that the micrograph of polyaniline is mesoporous with highly agglomerated granular shaped. The grains are well interconnected with each other, which indicate that they have enough binding energy to combine with neighbor grains or molecules.

4.2(b) show the SEM image of PANI- NiO composite. The complexes are softened after the addition of NiO into PANI matrix and it is also well understood that the NiO particles are homogeneously distributed and greatly intercalated within the matrix.

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Preparation of Polyaniline/Nickel Oxide Nanocomposites and Evaluation of its Electrical Properties (IJSTE/ Volume 2 / Issue 08 / 010)

Surface Area Analysis:

Fig. 4.3(a): shows the Surface area graph of Pure Nickel oxide nanoparticles

Fig. 4.3(b): shows the Surface area graph of Polyaniline /NiO composite 50wt%

Figures 4.3(a&b) shows the surface area of pure Nickel oxide and PANI/Nickel oxide composites. From the above figure, it is clearly seen that the NiO particles shows higher surface area compared to PANI/NiO composite. It is found in the nanocomposite, the surface area decreases because of PANI macro molecules are combined with NiO oxide nanoparticles.

Transmission Electron Microscopy:

Fig. 4.4: shows the SEM image of Pure Nickel oxide nanoparticles

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Preparation of Polyaniline/Nickel Oxide Nanocomposites and Evaluation of its Electrical Properties (IJSTE/ Volume 2 / Issue 08 / 010)

TEM image of the NiO nanoparticles obtained at 300◦C for 2 h is shown in Figure 4. According to the image, the sample is composed by crystalline particles. The shape of the nanoparticles varies from nearly spherical to ellipsoidal and irregular morphologies. The average particle size is 200 nm. From the images, the exact morphology of the NiO nanoparticles is hard to estimate. Highly disordered regions are visible, where a long-range crystalline order is not clearly observed.

V. DC CONDUCTIVITY STUDIES -5

2.4x10

-5

2.2x10

Pani 10wt% 20wt% 30wt% 40wt% 50wt%

-5

2.0x10

-5

1.8x10

-5

1.6x10

-5

dc(S/cm)

1.4x10

-5

1.2x10

-5

1.0x10

-6

8.0x10

-6

6.0x10

-6

4.0x10

-6

2.0x10

0.0 20

40

60

80

100

120

140

160

180

200

o

Temprature ( C) Fig. 5: shows the σdc conductivity as a function of temperature for PANI /NiO composites

Figure: 5 shows the σdc conductivity as a function of temperature for PANI /NiO composites at various weight percentages. It is observed that the conductivity of the composites increases with increase in temperature ranging from 30 0C to 1800C. Among all the composites 30 wt% shows higher conductivity. This clearly indicates that the conductivity is not only the motion of ions (NiO) but also hopping of charge carriers like polarons and bipolarons from one island to another. 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. Also, there will be molecular rearrangement on heating which makes the molecules favorable for electron delocalization. The conductivity varies directly with the temperature obeying an expression of the following form. σ (T) = σ0 exp [ - (T0/T) ¼] ……………(1) Where σ is the conductivity, T is the temperature, and σ0 is the conductivity at characteristic temperature T0.Conductivity varying with various values of the exponent (e.g.T-1/4, T-1/3and T-1/2) has been reported and different models have been used to interpret this data.

VI. CONCLUSION Polyaniline—NiO composites were synthesized by in-situ polymerization method. The prepared composites were characterized

by XRD for structural information, SEM and TEM for surface morphology. Further, the DC conductivity was studied by two probe method and it is found that the conductivity increases with increase in temperature as well as NiO wt% percentages in PANI. Among all composites, 50 wt% shows high conductivity. This increase in conductivity is due to the elongation of polymer chain length and hopping of polarons it also shown that the pure NiO shows higher surface area compared to pure Polyaniline.

Hence these composites are promising materials for potential applications.

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Preparation of Polyaniline/Nickel Oxide Nanocomposites and Evaluation of its Electrical Properties (IJSTE/ Volume 2 / Issue 08 / 010) [8] Tiwari, A. Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, 2007, 44(7), 735. DOI: 10.1080/10601320701353116 [9] Kondawar, S.B.; Thakare, S.R.; Bompilwar, S.; Khati, V. Int. J. Mod. Phys. B, 2009, 23 (15), 3297. DOI: 10.1142/S0217979209052583 [10] Tiwari, A.; Prabaharan, M.; Pandey, R.; Li, S. Journal of Inorganic and Organometallic Polymers and Materials, 2010, 20(2), 380. DOI: 10.1007/s10904010-9354-9 [11] Kondawar, S.B.; Acharya, S.A.; Dhakate, S.R. Adv. Mat. Lett. 2011, 2(5), 362. DOI: 10.5185/amlett.2011.9107am2011 [12] Sharma, A. K.; Sharma, Y.; Malhotra, R.; Sharma, J.K. Adv. Mat. Lett. 2012, 3(2), 82. DOI: 10.5185/amlett.2012.1315 [13] Ziębowicz, B.; Drak M.; Dobrzański, L.A.; J. Achiev. Mater. Manuf. Engin. 2007, 191, 352. DOI: 10/1016/j.jmatprotec2007.03.029 [14] Srivastava, A.K.; Thota, S.; J. Nanosci. Nanotech. 2008, 8(8), 4111. DOI: 10.1166/jnn.2008.aN36 [15] Ichiyanagi, Y.; Wakabayashi, N.; Yamazaki, J.; Yamada, S.; Kimishima, Y.; Komatsu, E.; Tajima, H. Phys. B, 2003, 862, 329. DOI: 10.1016/S09214526(02)02578-4 [16] Karthik, K.; Selvan, G. K.; Kanagaraj, M.; Arumugam, S.; Jaya, N. V.; J. Alloy. Comp. 2011, 509 (1), 181. DOI: 10.1016/j.jallcom.2010.09.033 [17] Li X.; Zhang X.; Li Z.; Qian Y.; Solid State Commun. 2006, 137(11), 581.

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