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European Journal of Applied Sciences – Vol. 12, No. 2

Publication Date: April 25, 2024

DOI:10.14738/aivp.122.16654

Assem, H. D., Agyei, M. S., Tamakloe, R. Y., Nkum, R. K., & Singh, K. (2024). Synthesis and Study of Electro-Optical Properties of

Water-Soluble Polyaniline Prepared by Chemical Oxidation. European Journal of Applied Sciences, Vol - 12(2). 215-240.

Services for Science and Education – United Kingdom

Synthesis and Study of Electro-Optical Properties of Water- Soluble Polyaniline Prepared by Chemical Oxidation

Humphrey Darkeh Assem

Department of Physics, Kwame Nkrumah University Science

and Technology Kumasi-Ghana (West Africa)

Mensah Samuel Agyei

Department of Physics, Kwame Nkrumah University Science

and Technology Kumasi-Ghana (West Africa)

Reuben Yao Tamakloe

Department of Physics, Kwame Nkrumah University Science

and Technology Kumasi-Ghana (West Africa)

Robert K. Nkum

Department of Physics, Kwame Nkrumah University Science

and Technology Kumasi-Ghana (West Africa)

Keshaw Singh

Department of Physics, Kwame Nkrumah University Science

and Technology Kumasi-Ghana (West Africa)

ABSTRACT

Due to its environmental stability and decent levels of conductivity, polyaniline has

recently become one of the more promising conducting polymers; nonetheless, the

solubility of the conducting polymers is vital for their uses. The solubility of pure

polyaniline (PANI) in water is limited. However, in this research, we successfully

synthesized water-soluble complexes of PANI by chemically oxidizing aniline in an

aqueous solution containing cellulose derivatives such as methylcellulose (MC),

hydroxypropyl cellulose (HPC), and hydroxypropyl methylcellulose (HPMC). The

synthesis process involved using aniline as the monomer, hydrogen chloride (HCl)

as an acidic dopant, ammonium persulphate (APS) as an initiator, and cellulose

derivatives as a steric stabilizer. The resulting PANI composites were easily

dissolved in deionized water. To create thin films by the spin coating technique, the

PANI composite solutions were coated onto ITO glass substrates at different RPM

speeds (1000, 2000, and 3000) for 2 minutes. The thickness of the films ranged from

50 nm to 80 nm. Four characterization techniques were employed to study the

electro-optical properties of the prepared samples. Fourier Transform Infrared

Spectroscopy (FTIR) was employed to confirm the chemical structure of the PANI

complexes, which exhibited distinctive peaks at 3460 cm-1. The interaction between

PANI and cellulose derivatives was examined using ultraviolet-visible spectroscopy

(UV-Vis) in the wavelength range of 200 nm to 700 nm. The absorbance showed a

sharp increase and a red shift around 500 nm, which was further supported by

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Services for Science and Education – United Kingdom 216

European Journal of Applied Sciences (EJAS) Vol. 12, Issue 2, April-2024

extrapolated bandgap values. For electrical conductivity measurements, we

employed the Standard Four-Point Probe Method. The observed electrical

conductivity followed the order of PANI > HPC > MC > HPMC, with values ranging

from 1.32 x 10−2

to 6.81 x 10−2 S/cm for the bulk samples. Similar trends were

observed for the thin films. XRD characterization confirmed the presence of PANI

and cellulose derivative traces, as indicated by distinct peaks at various two theta

angles.

Keywords: Conducting polymers, polyaniline, cellulose derivatives, spin coating,

electrical conductivity, XRD, FTIR, UV-VIS, water soluble.

INTRODUCTION

Energy obtained from natural resources that can be replenished in less than a human lifetime

without diminishing the planet's resources is known as renewable energy. The advantage of

these resources is that they are almost universally accessible in one way or another. Examples

of these resources include sunshine, wind, rain, tides, waves, biomass, and thermal energy

stored in the earth's crust. They practically never run out. They also don't harm the climate or

the environment much, which is even more significant. Despite the availability of these

renewable sources of energy, additional energy storage components are essential for the

utilization of renewable energy sources and they play a significant role in the efficient, clean,

and varied use of energy. Because of this, research, development, and industrialisation efforts

have been focused heavily on energy storage materials, which include a variety of materials.

Thin films made from conducting polymers are making a significant impact in the 21st century.

Applications of these materials have been seen in several fields including energy storage

devices like capacitors and solar cells. Conjugated polymer blends of thin films which can be

used for making light emitting diodes are excellent alternatives to inorganic semiconductor

materials because of their easy processability , low-cost fabrication , and mechanical

flexibility. The types of these conjugated polymers include Poly (acetylene) s, Poly (pyrrole)s,

Poly (thiophene)s and Poly (aniline)s (Kularatne et al. 2013). The addition of inorganic

semiconducting nanoparticles to these conducting polymers can effectively improve their

electrical, optical and dielectric properties. The power crisis in Ghana has called for alternative

energy solutions including means by which power could be stored. This study seeks to harness

the best synthesizing method of conducting polymer thin films for a potential application.

Polymers often act as insulators. This means that conducting polymers are likely to have an

unusual structure. Low energy optical transitions, low ionization potentials, and high electron

affinities are few peculiar electrical characteristics that polymers with conjugated -electron

(C=C conjugated links) backbones exhibit (Skotheim 1986). As a result, a new family of

polymers has been created that can be reduced or oxidized more quickly and with greater

reversibility than traditional polymers. When manufactured under suitable circumstances and

with the proper parameters, PANI and other related polymers have demonstrated that they

contain semiconducting characteristics. PANI has relatively low toxicity, is stable in aggressive

chemical environments, with high thermal stability and low fabrication cost. One can only hope

that these advantageous PANI features will be utilized for high efficiency in the realm of

technology, which is why this inquiry is necessary.

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Assem, H. D., Agyei, M. S., Tamakloe, R. Y., Nkum, R. K., & Singh, K. (2024). Synthesis and Study of Electro-Optical Properties of Water-Soluble

Polyaniline Prepared by Chemical Oxidation. European Journal of Applied Sciences, Vol - 12(2). 215-240.

URL: http://dx.doi.org/10.14738/aivp.122.16654

Engineers have worked to create smaller, more powerful batteries as things get smaller and

smaller and that has meant packing more energy into smaller spaces. Energy density is one

metric to gauge this tendency. Calculate it by dividing the battery's volume by the amount of

energy it can hold. A battery with a high energy density contributes to the weight reduction and

portability of electronic gadgets. Additionally, it makes them operate longer between charges.

Instead of including chemical changes, energy storage by a capacitor just necessitates the

establishment of an excess and a deficit of electron charges on the capacitor plates on charging

and the opposite on discharging. As a result, a capacitor can be recycled an almost infinite

number of times, usually between 105 and 106. Because of their higher power and energy

densities, which are considered to be ideal power sources for applications like digital

communication, portable systems, electric vehicles, and other similar ones, efforts to develop

better supercapacitors have gained importance. Because some batteries contain chemicals that

aren’t eco-friendly, they must be recycled. This is one reason engineers have been looking for

other ways to store energy.

The term "supercapacitor" refers to a component that engineers developed recently. It

combines a capacitor and a battery. Like a capacitor, the supercapacitor has two conducting

surfaces. As in batteries, they are referred to as electrodes. The supercapacitor, as opposed to

a battery, instead stores energy on the surface of each of these electrodes. Because

supercapacitors' electrodes have far greater surface areas than conventional capacitors, they

can hold more electrical charge than conventional capacitors. Supercapacitors' performance

can be enhanced by adding sulfonated polyaniline/graphene composites (Ates et al. 2015, Zang

et al. 2008, Sharma & Desu 2008, and Ou and Xu 2016). By covering the electrode with a very

large number of extremely small particles, engineers increase the surface area. When the

particles are combined, a rough surface is created that covers a lot more surface area than a flat

plate would. Because of that, this surface can store much more energy than a conventional

capacitor. Due to many doping forms of conducting polymers and the various types of doped

conducting polymer capacitors, conducting polymers can be employed as a supercapacitor

electrode material in various ways. Conductive polymer capacitors come in three different

major categories. According to Hanemann and Szabó (2010), the first type is made up of an

entirely identical p-type doped conductive polymer. This type of capacitor discharge only

releases half of the charge, and the potential difference between the two poles is minimal. The

second type of capacitor is made of various conducting polymers, and both of them can have p- type doping added to them. The potential range of doping is diverse according to the various

conductive polymer electrode materials, allowing the capacitor to have a greater voltage

differential when fully charged (Zheng J. P. 2003; Emel & Mustafa 2013). The ability of this type

of supercapacitor to discern between positive and negative is insufficient, and it cannot be

reverse charged, which restricts the applications for capacitors and affects their cycle life. The

final type one is made up of a doped n-type electrode and a doped p-type electrode. The cathode

of the capacitor is entirely doped in the fully charged state, while the positive electrode is fully

doped in the fully discharged state, increasing the voltage differential between the two

electrodes. The key benefits of such a capacitor structure include higher capacitor voltage,

complete charge release, the incorporation of two charging electrodes, and increased charge

storage capability.