Correlation between ion-exchange properties and swelling/shrinking processes in hexasulfonated calix[6]arene doped polypyrrole films: ac-electrogravimetry and electrochemical atomic force microscopy investigations

Abstract

. Correlation between ion-exchange properties and swelling/shrinking processes in hexasulfonated calix [6]arene doped polypyrrole films: ac-electrogravimetry and electrochemical atomic force microscopy investigations. Electrochimica Acta, Elsevier, 2011Elsevier, , 56 (10), pp.3516-3525. <10.1016Elsevier, /j.electacta.2010 -00811845> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Unexpectedly, within the potential range encompassing this process, K + cations were found to be exchanged for more cathodic potentials whereas H 3 O + are exchanged for more anodic potentials. EC-AFM investigations revealed substantial shrinking and swelling during the oxidation (doping) and reduction (undoping) processes respectively. An obvious correlation can easily be built between these observations: the oxidation of the polymer films provokes an expulsion of the cations, as expected from cation exchanger polymer films, and therefore a decrease of the volume (and thickness) of these films whereas their reduction causes an insertion of cations and an increase of their volume (and thickness). This electromechanical mechanism is amplified by the simultaneous exchange of free water molecules. Suggestions based on these observations, on structural characteristics of polypyrrole films, and on complexation ability of hexasulfonated calix [6]arenes incorporated in the films are discussed to explain i) the change of the identity of the exchanged cations as a function of the potential, ii) the exchange of free water molecules and, iii) the exchange of small amounts of nitrate ions.

Electrochemically induced free solvent transfer in thin poly(3,4-ethylenedioxythiophene) films

“…Therefore, a constant thickness of films cannot be considered since it may change depending on the polarization potential [38][39][40][41].…”

Photo-assisted electrodeposition of an electrochemically active polypyrrole layer on anatase type titanium dioxide nanotube arrays

“…doping) state of the growing conducting polymer film and are responsible for its ion exchange properties. It is well-known that the chemical composition of the electrolytic solution, and in particular, the type and size of the ions of the background salt present in the electrolyte are determining for the ion exchange behaviour of conducting polymers [9] and enable to control their electrochemical properties [10]. For instance, PPy films doped with large anions such as dodecylbenzenesulfonate (DBS) anions are expected to be mainly cation exchangers as a consequence of the irreversible entrapment of DBS -anions in the polymer matrix, unlike PPy/ClO 4 -that are mainly anion exchanger films.…”

Electrochemical and viscoelastic evolution of dodecyl sulfate-doped polypyrrole films during electrochemical cycling

“…Electrochemical quartz-crystal microbalance (EQCM) and its coupling with electrochemical impedance spectroscopy (the so-called ac-electrogravimetry) have proved themselves as baseline analytical tools to probe electrochemical processes, with tremendous benefits in in situ capturing ionic fluxes in various electrodes, including 3 carbon based electrodes [24][25][26] and CPEs [27,28]. Considerable amount of work has focused on the exploration of electrochemical properties of CPEs, which has been regarded as a prerequisite for improving performances of electrochemical devices [29,30].…”