Characterization of the Viscoelasticity and the Surface Roughness of Electrochemically Prepared Conducting Polymer Films by Impedance Measurements at Quartz Crystals

Abstract

The electrical impedance of quartz crystals was measured during electropolymerization of poly (2,2Ј-bithiophene) ͑PBT͒ and poly-͑3,4-ethylenedioxythiophene͒ ͑PEDT͒ from acetonitrile and propylene carbonate. Due to the viscoelastic behavior and the high surface roughness, application of the Sauerbrey equation to relate frequency shifts to mass changes leads to systematic errors. A novel procedure is presented to calculate the mass changes, the viscoelastic properties ͑complex shear modulus͒, and the surface roughness of the conducting polymer layers from the shift of the resonance curve of the quartz crystal. The dependence of the surface morphology of PEDT and PBT on the preparation conditions could be monitored in situ. The values of the complex shear moduli show that these polymers have rubber-like behavior. The damping increase of the quartz at the initial stages of the polymer deposition is mainly a surface roughness effect. As the polymer thickness increases, internal friction ͑viscoelasticity͒ also begins to contribute to the damping.

Electrochemical lithiation of thin silicon based layers potentiostatically deposited from ionic liquid

“…In parallel to the frequency change the damping increases approximately twice the frequency shift. Therefore, at these conditions an accurate mass evaluation of the deposited silicon from the frequency change using the Sauerbrey equation cannot be performed, as shown in the studies describing QCM application and theoretical principles of the method [43,44].…”

Improvement of protection performance of polypyrrole by dopant anions

“…In EQCM measurements, the working electrode was an 'AT-cut' 10 MHz quartz crystal (15 mm in diameter) with Au electrodes on a chromium adhesion layer provided by KVG (Neckarbischofsheim, Germany) [17]. They were held between two O-ring gaskets (active area 0.23 cm 2 ).…”

“…The change of polymer mass was calculated with the Sauerbrey equation Df=C SC Dm. The Sauerbrey constant is C SC =226.01 Hz cm 2 lg )1 for a 10 MHz quartz [17,22].…”

“…The difference in the mass after one cycle derives from the difference in the molar mass of molybdate and bromide. From the ratio of the mass change and the electrical charge passed Dm/Q in Figure 5 the molar mass of molybdate (M=131 g mol )1 ) was calculated [17,23]. It is compared with the real molar mass in the form MoO 4 M= 159.94 g mol )1 .…”

Viscoelastic potential-induced changes in acoustically thin films explored by quartz crystal microbalance with motional resistance monitoring

“…The transmission of acoustic wave from the electrode surface to the film depends on these forces. In the film|solution interface, the film roughness defines the friction between the film surface and the liquid [20,46]. Formation and destruction of covalent bonds in the macromolecular backbone changes the polymer structure of ICP during the potential sweep.…”