Studies on electrochemically synthesized polyaniline and its copolymers
Loading...
Date
2009
Authors
Parsa, Ali
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Oxidative electropolymerization of aniline in phosphoric acid on 2B pencil
composite graphite was accomplished using some selected inorganic salts as
supporting electrolytes. These salts determined the degree of conductivity of
polyaniline formed, in the order of CaCl2 > KCl > ZnCl2 > ZnSO4 > Ca3(PO4)2. The
presence of either 0.06 M Ca3(PO4)2 or 0.2 M ZnSO4 in the synthesis of polyaniline
have caused the shifting of its redox peaks as much as 250 mV to the negative
potential. The shifting of these peaks was only influenced by type of anions presence
not the cations. This incident has prompted the formation of copolymer aniline and
ortho-phenylenediamine.
The morphology of the homopolymer polyaniline films was also examined by
a field emission scanning electron microscope and energy dispersive X-ray
diffraction. The results showed that surface morphology of the homopolymer was
dependent on the electrolytes used. The surface morphology also dictated each
inorganic salt into different bloom-like crystal formations.
The homopolymer synthesised in different salts has its antioxidant capacity
increased. The phosphate medium polyaniline was a strong reducing agent, capable
of scavenging 1,1-diphenyl-2-picrylhydrazyl radical in methanol. It was twice more
effective as an antioxidant than the chloride medium polyaniline.
The anodic homo and copolymerization of aniline and pyrrole on composite
graphite in aqueous para-toluene sulphonic acid with and without potassium chloride
(KCl) were investigated. The presence of KCl in the medium has improved the
structural, optical and morphological properties of the resulting polymers. The X-ray
photoelectron spectroscopy confirmed that poly(aniline-co-pyrrole) synthesized in
the presence of KCl has nearly equal units of both pyrrole and aniline in the
polymeric backbone as compared to the one synthesized in absence of KCl.
The inherent negative shift of redox peaks of polyaniline has also been
investigated in the copolymerization of aniline and ortho-phenylenediamine on
composite graphite. The poly(aniline–co–ortho-phenylenediamine) modified
composite graphite showed excellent electro catalytic response towards the oxidation
of ascorbic acid. The anodic peak potential of ascorbic acid has been shifted from
+0.5 V vs. Ag/AgCl (at bare composite graphite) to +0.1 V vs. Ag/AgCl (at
poly(aniline–co–ortho-phenylenediamine) modified composite graphite), indicating
easier electrode process of ascorbic acid on the later.
Description
PhD
Keywords
Chemical science , Electrochemically , Synthesized polyaniline , Copolymers