Obtenção e caracterização eletroquímica do compósito polipirrol
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Data
2002-04-15Autor
Bello, Maria Elvira do Rêgo Barros
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This study was carried out to investigate the electrochemical
preparation of a composite polypyrrole / cobalt, as well as your characterization
physical-chemistry. The composite was electropolymerized on a platinum
substrate in aqueous solution with lithium perchlorate. It was characterized
electrochemically with cyclic voltammetry. A voltammetric behavior quite
differentiated between the pure polypyrrole and the composite it was observed,
above all, for the pronounced cathodic peak that appeared in the voltammogram
of the composite, which was attributed to the metallic deposition. The
interesting in this case was that the cathodic peak appeared in a more positive
potential in the composite than when verified on pure platinum. Besides, it was
observed although in presence of the cobalt the redox processes in the polymeric
suffered a potential displacement. Such results suggested the presence of an
interaction between the metallic cobalt and the polymeric phase, possibly a
complexation between the cobalt and the polypyrrole. A morphological analysis
of the film was made by scanning electronic microscopy, having observed a
more regular surface and with smaller nodules for the material of the composite.
The X-ray difractometry of the films it was also done, but it didn't take to
conclusive results. A chemometrics study was accomplished through 22 factorial
design involving the synthesis variables and the voltammetric analysis variables
of the composite, while optimization procedures, using the response surface
methodology, was accomplished with the intention of increasing the
intercalation of the cobalt in the polymeric phase. As a measure of the
intercalation, it was taken the parameter current density of cathodic peak of the
process regarding the cobalt. The results showed an increase of 73.7% in this
current density of cathodic peak for the film synthesized in the optimized
condition, in comparison with the largest value found before the optimization.