In situ monitoring of the electrochemical degradation of polymer films on metals using the bending beam method and impedance spectroscopy

Structural changes during the overoxidation of electrochemically deposited poly(3,4-ethylenedioxythiophene) films

“…[22], the bending beam method offers the possibility to measure the changes of the stress in thin polymer films but the contributions from surface and bulk cannot be separated in the general case, therefore only the "voltdeflectograms", i.e. the ΔR -1 vs. E plots are shown in Fig.…”

“…In [22] EQCM experiments have been carried out to evaluate the correlation between mass loss and electrochemical measurements. It has been shown during the potential cycling in the "stable region" the EQCM frequency changes periodically and the average remains practically the same.…”

“…The refractive indexes were measured at 25.0 °C with a Zeiss PR 2 refractometer and, based on the Cauchy parameters, the refractive index at 632.8 nm (see Table 1 in Ref. [22]) was calculated. A He-Ne laser (Melles Griot 05-LHP-151, 1 mW, operating at a wavelength of 632.8 nm) was used in our electrochemical bending beam measuring system [43].…”

“…[20][21][22] that at sufficiently positive electrode potentials, degradation ("overoxidation") of the polymer takes place. That is, when the positive potential limit of the cyclic voltammogram (CV) is extended to the region in which the overoxidation of the polymer film takes place, an oxidation peak (without a corresponding reduction peak) appears in the CV.…”

“…[16] and [22] it has been shown that PEDOT films in modified electrodes undergo structural changes during the overoxidation (degradation) process. The most probable stages involved in the overoxidation/degradation process are: 1) Overoxidation results in stress generation in the PEDOT film [23].…”