Open Access Library Journal
How to cite this paper: Alemayehu, T. and Abiebie, D. (2014) Preparation of Poly Aniline by Chemical Oxidative Method
and Its Characterization. Open Access Library Journal, 1: e974. http://dx.doi.org/10.4236/oalib.1100974
Preparation of Poly Aniline by Chemical
Oxidative Method and Its Characterization
Tassew Alemayehu, Diribe Abiebie
College of Natural and Computational Sciences, Department of Chemistry, Adigrat University, Adigrat, Ethiopia
Received 10 July 2014; revised 15 August 2014; accepted 20 September 2014
Copyright © 2014 by authors and OALib.
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Abstract
The present work reports the oxidative synthesis of poly aniline using K2Cr2O7 as an oxidizing
agent and H2SO4 as dopant. The synthesized polymer was characterized by solubility test and UV-
visible spectroscopic technique. The synthesized polymer (poly aniline) was insoluble in ethanol,
acetone, benzene and water. The absorbance of UV-visible spectra shows two reductive peaks at
some wake length. The band observed at 327 - 365 nm for the PANI samples corresponds to n-p*
transitions of aniline and the broad band at 600 - 620 nm is due to n-p* transitions of quinine-im-
ine groups.
Keywords
Doping, Poly Aniline, UV-Visible Spectra, Solubility Test
Subject Areas: High Polymer Chemistry, Organic Polymer Materials
1. Introduction
Polymers are high molecular weights which built up a large number of small molecules called monomers (low
molecular weight substance which when redacted under suitable conditions links together to produce high mo-
lecular weight polymer). Some of two or three different units repeat a number of times in a polymer. In the
laboratory the preparation of polymers involves looking together of many small molecules [1].
Polymers can be classified in several different ways according to their structures, physical properties or types
of reaction by which they undergo. However, these classifications are not independent of each others. On the
basis of their structure, we can split polymers into two main types. These are homo polymer and copolymers. In
homo polymers there is only one monomer unit present. But in copolymer we have two or more different
monomer units [2].
Aniline is an organic base used to make dyes, drugs, explosive, plastics and photographic and rubber chemical
and was first obtained in 1826 by the destructive dis tillation of indigo. Its name is taken from the specific name

T. Alemayehu, D. Abiebie
OALibJ |
DOI:10.4236/oalib.1100974 2 September 2014 | Volume 1 |
e974
of the indigo-yielding plant indigo era anile with chemical formula of C6H5NH2. Aniline is prepared commer-
cially by catalytical hydrogenation of nitro benzene or by the action of ammonia on chlorobenzene. In an acidic
medium, nitrous acid converts aniline into adiazonium salt that is an intermediate in the preparation of a great
number of dyes and other organic compounds. Pure aniline is a highly poisonous and colorless substance with a
pleasant odor [3] [4].
Poly aniline was first know in 1835 as “Aniline black”, a term used for product obtained by the oxidation of
aniline, the interest in poly aniline as an important cond ucting polymer has incr eased significantly over the past
decade. The poly anilines refer to a large class of conducting polymers which have the following general for-
mula represented in Figure 1 below [5].
1.1. Objective
1.1.1. General Objective
The main objective of this study relies on the preparation of poly aniline by chemical oxidative method and
characterizing it.
1.1.2. Specific Objective
To attain this main objective the following specific were include like familiarizin g with preparation methods of
poly aniline, studying the solubility of poly aniline and familiarizing with the poly aniline characterization
methods.
2. Methodology
2.1. Equipments and Chemicals
Equipments employed or used in this work include suction filtration, UV-visible spectrometry, filter paper,
dropper, beaker, volumetric flask, round bottom flask, stirrer, electronic balance, mortar, pestil grinder, elec-
tronic centrifugation, and measuring cylinder.
Chemicals
The chemicals used in this work were also H2SO4, K2Cr2O7, aniline, ethanol, acetone, benzene, and distilled
water.
2.2. Solution Preparation
1) 0.04 M of K2Cr2O7 was prepared by dissolving 2.94 g of K2Cr2O7 in 250 ml volu metr ic fla sk w ith distilled
water.
Calculation M = C × V(L) × MWt
= 0.04 M × 0.25 L × 294.18 g/mo l
= 2.94 g
2) 0.1 M of H2SO4 was pre pa r e d by diluti ng 1.39 ml H2SO4 in 250 ml volumetric flask with distilled water.
For solution preparation fro m liquids its formula is as follow.
C1V1 = C2V2 from dilution law. V1 = C2V2 = 0.1 M × 0.25l = 1.39 ml
C1 18 m
3) 0.1 M of aniline (l) was prepared by diluted 2.34 ml of aniline in 250 ml of volumetric flask with distilled
water.
Figure 1. General formula of poly aniline [6].

T. Alemayehu, D. Abiebie
OALibJ |
DOI:10.4236/oalib.1100974 3 September 2014 | Volume 1 |
e974
C1V1 = C2V2V1 = C2V2 = 0.1 m × 0.25 L = 2.34 ml
C1 10.7 m
2.3. Experimental Procedures
In this experiment to prepare poly aniline 50 ml of 0.1 M of aniline was taken into 250 ml volumetric flask and
50 ml of 0 .1 m H2SO4 was added. Again at appropria te oxidant 20 ml of 0.04 m K2Cr2O7 aqueous solutions was
slowly added to the reaction medium for about 20 minutes by using dropping funnel and the precipitate was
formed. Then the precipitate formation on the polymerization reaction was filtered at the end of final product by
using suction filtration. Again the final product was washed by using diluted solution of H2SO4 and dried at
60˚C in vacuum for 12 hours. Then the synthesized product (poly aniline) was grinded by using grinder and the
solubility of the powder was checked in different solvents like acetones, benzenes, ethanol and water was
checked and absorbance value was recorded using UV-Vis spectrophotometer.
3. Result and Discussion
1) Solubility
The Solubility of sulfuric acid doped poly aniline was analyzed in various solvents. Sulfuric acid dop ed PANI
was insoluble in solvents like acetone, benzene, methanol and water. According to some literatures PANIS is
Soluble in DMSO but there was no DMSO at the laborator y to check the solubility [6].
2) Absorbance measurement
The UV-visible spectra of the PANI synthesized with the use of K2Cr2O7 in H2SO4 media was measured by
dissolving 0.057 g of poly aniline green powder in 10 ml of H2O that was placed in to electronic centrifugation
at 600 revolving frequency for 10 minutes to measure its Absorbents different wave lengths. The absorbance of
PANI was recorded as show in the following (Table 1).
Figure 2 shows the graph of wavelength versus absorbance of poly aniline. In the figure absorbance repre-
sented as Abs is plotted at the y-axis ranging from 0 to 1 and wavelength in nanometer (nm) is plotted at the
X-axis ranging from 250 nm to 600 nm. As can see in the figure poly aniline gives two reductive peaks occur at
around 350 nm and 600 nm wave lengths. Aniline has a good ability of absorbance around 0.96 at 350 nm wave
Table 1. Absorbance of PANI at different wave lengths.
λ (nm) Absorbance
350 nm 0.958
450 nm 0.108
550 nm −0.301
650 nm 0.054
750 nm −0.040
Figure 2. Plot of absorbance peak at y-axis for poly aniline at dif-
ferent wave lengths at x-axis.

T. Alemayehu, D. Abiebie
OALibJ |
DOI:10.4236/oalib.1100974 4 September 2014 | Volume 1 |
e974
length. The band observed at 350 nm for the PANI samples corresponds to n-π* transitions of aniline. The broad
band’s at 600 - 620 nm is due to n-π* transitions of amine groups [6].
The reaction that represents prep a ration of poly aniline is as follow.
4. Conclusion and Recommendation
4.1. Conclusion
In this research the result shows that the synthesized H2SO4 doped poly aniline is in soluble in solvent like ace-
tone, benzene, methanol, and water. Based on the closeness of UV-visible absorbance, results of this stud y with
other related works indicated in review are possible to say that poly aniline can be synthesized by chemical po-
lymerization method based on oxidative coupling in which this coupling involves oxidation of monomers to
form a cation radical double by coupling called a dication.
4.2. Recommendation
Based on this study it is recommended that it is advisable to prepare polymers like poly aniline by chemical
oxidative method even in the absence of well organized laboratory.
References
[1] Nunziante, P. and Pistoia, G. (1989) Conducting Polymers. ElectroChem, 34, 223.
[2] Maria, C. (2008) Organic Chemistry of Polyanilines. The Open Macromolecules Journal, 1, 58-73
[3] Cheruku, D. (2008) Electronic Devices and Circuits. 2nd Edition.
[4] Odian, G. (2004) Principles of Polymerization. 4th Edition, Wiley-Interscience, New York.
[5] Trivedi, D.C. (1997) Polyanilines. In: Nalwa, H.S., Ed., Handbook of Organic Conductive Molecules and Polymers,
Conductive Polymers: Synthesis and Electrical Properties, Vol. 2, John Wiley & Sons, New York.
[6] Vivekanandan, J., et al. (2011) Synthesis, Characterization and Conductivity Study of Poly Aniline Prepared by
Chemical Oxid ative and Electrochemical Methods. Archives of Applied Science Research, 3, 5.