Facile synthesis and characterization of polypyrrole-multiwalled carbon nanotubes by in situ oxidative polymerization
International Nano Letters
Facile synthesis and characterization of polypyrrole-multiwalled carbon nanotubes by in situ oxidative polymerization
Amin Imani 0
Gholamali Farzi 0
Adnen Ltaief 0
0 Department of Materials and Polymer Engineering, Faculty of Engineering, Hakim Sabzevari University , P.O. BOX397, Sabzevar , Iran
Polypyrrole-multiwall carbon nanotube (PPy-MWCNT) nanocomposites were chemically synthesized via in situ oxidative polymerization of pyrrole. Ammonium peroxydisulfate and p-toluenesulfonic acid were used as an initiator and surfactant dopant, respectively. The molar ratio of monomer unit to initiator and dopant was 1:1:1, and the percentage of MWCNT in PPy varied from 1 to 10 wt.%. PPy-MWCNT nanocomposites were characterized to study chemical structure, morphology, thermal, electrical, and surface properties. To accomplish this, the samples have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, four probe resistivity method, and atomic force microscopy. The results showed that PPy-MWCNT nanocomposites were successfully synthesized via in situ oxidative polymerization method, and also, electrical conductivity of nanocomposites was increased when the content of MWCNT increase.
Polypyrrole; Multiwall carbon nanotubes; Nanocomposites; Oxidative polymerization; Conductivity; AFM
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Background
It appears that one of the most important group of
materials are the conducting polymers with a vast field of
applications from primarily passive materials such as
coatings and containers to active materials with useful
optical, electronic, energy storage, and mechanical
properties. They are synthesized either by reduction or
oxidation reaction, which is called doping process. Among
several conducting polymers, polypyrrole (PPy) has
attracted much attention from researchers due to its
unique properties such as high conductivity, simple
methods of preparation, simply synthesis as a composite
matrix, stability, and good mechanical properties. Due to
these exceptional properties, it has many potential
applications in electronic and electrochromic devices,
corrosion protection, rechargeable and lightweight batteries,
drug delivery, membrane separation, supercapacitors,
and sensors [1-4].
PPy was first synthesized by chemical polymerization
during the early nineteenth century [5]. It was found
insoluble in most of the common solvents due to the
strong interchain interaction. Usually in chemical
polymerization, oxidative agents initiate the chemical
reaction. Such a method allows us to categorize oxidative
polymerization of pyrrole as a new area in cationic
polymerization, in which the conditions of initiation,
propagation, and termination of the chains can be said
by means of the electrochemical potential of the system.
Oxidative polymerization exemplifies a new means to
access conducting polymers, and it is one of the important
green chemistry processes to prepare multifunctional
polymers. This method has been widely used to prepare
different types of conducting polymers [6,7] and their
different derivatives [8].
PPy can be made chemically through oxidative
polymerization of pyrrole. In this neutral state of the
PPy, it is not conductive and only becomes conductive
when it is oxidized [9]. The charge related with the
oxidized state is naturally delocalized over some pyrrole
units and can form a radical polaron or a bipolaron [10].
It has also been recognized to be very easy to prepare
PPy particles of different sizes ranging from micrometers
to nanometers with the addition of different dopants
[11]. Nevertheless, PPy provides suitable properties, but
to adjust the polymer attributes and attain excellent
properties, they have been used in composites structure
by combining with nanoparticles such as carbon
nanotubes (CNT) [12,13]. In general, nanocomposite materials
with CNT can show different mechanical, electrical,
optical, electrochemical, catalytic, and structural properties
than those of each individual component. The
multifunctional behavior for any specific property of the material is
often more than the sum of the individual components
[2]. CNT also have received important concentration for
their unique mechanical, electrical, thermal, and magnetic
properties that have been used in the field of
nanocomposites materials, nanodevices, and so on [4]. The
large specific area and aspect ratio of multiwall carbon
nanotubes (MWCNTs) have made them efficient as
conductive fillers in polymers [14].
In this work, PPy-MWCNT nanocomposites were
prepared via in situ chemical oxidative polymerization, and the
content of MWCNTs in the composites varied from 1 to
10 wt.%. The impact of different contents of MWCNTs on
the structures and properties of the PPy-MWCNT
nanocomposites were deeply discussed based on the results
from Fourier transform infrared spectroscopy (FT-IR),
Xray diffraction (XRD), thermogravimetric analysi (...truncated)