XII Iberian Meeting of Electrochemistry XVI Meeting of the ...

XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society PD 04
Electrochemical characterization of polypyrrole-based
conducting fabrics in different pH media
Javier Molina, Javier Fernández, Ana Isabel del Río, José Bonastre,
Francisco Cases
Departamento de Ingeniería Textil y Papelera, EPS de Alcoy, Universidad Politécnica de Valencia,
Plaza Ferrándiz y Carbonell s/n, 03801 Alcoy, Spain
jamopue@doctor.upv.es
Conducting fabrics of polyester covered with polypyrrole have been electrochemically
characterized at different pHs (1, 7 and 13). The stability of the conducting fabrics in
different pHs is fundamental in views of its application in electronic textiles or
electrocatalysis. In the study, two counter ions have been employed: AQSA (organic)
and PW 12 O 3- 40 (inorganic). The electrochemical techniques that have been employed for
the electrochemical characterization have been cyclic voltammetry (CV) and scanning
electrochemical microscopy (SECM). It has been demonstrated the influence of the scan
rate in the form of the voltammograms obtained. High scan rates (50 mV·s -1 ) did not
allow the observation of the redox processes and a resistive response was obtained. On
the other hand, low scan rates (1mV·s -1 ) allowed the apparition of the redox peaks. The
charge transfer is produced across the polymer chains since polyester is an insulating
material. Lower pHs produced a higher and more characteristic electrochemical
response due to the influence of protonation on the polypyrrole activity [1].
SECM allows the possibility of studying zonal electroactivity at its open circuit
potential. Approach curves were obtained by SECM for the samples of PPy/AQSA and
3-
PPy/PW 12 O 40 treated at different pHs. Positive feedback was obtained for all the
conducting fabrics samples, so the fabrics were electroactive. The degree of positive
feedback varied on the nature and the treatment of the polypyrrole layer. An increase in
the pH of the solution caused the loss of part of the counter ions as XPS measurements
have revealed and the layer electroactivity was affected. The organic counter ion was
more stable than the inorganic one at pH 13. This is due to a reaction of decomposition
that suffers the PW 12 O 3- 40 at pH>8.3 [2]. The PW 12 O 3- 40 decomposed into PO 3- 4 and
WO 2- 4 [2].
Acknowledgments: Authors thank to the Spanish Ministerio de Ciencia y Tecnología and European
Union Funds (F EDER) (contract CTM2007-66570-C02-02) and Universidad Politécnica de
Valencia (Programa de apoyo a la investigación y desarrollo de la UPV (PAID-05-08)) for the
financial support. J. Molina and A.I. del Río are grateful
(Generalitat Valenciana) and the Spanish Ministerio de Ciencia y Tecnología respectively for the
FPI fellowship.
References
[1] Krzysztof M. Electroanalysis, 2006, 18, 1537.
[2] Zu Z.; Tain R.; Rhodes C. Canadian Journal of Chemistry, 2003, 81, 1044.
September, 811, 2010. ISEL - Lisbon 86