Viscoelastic characteristics of electroactive polymer films

The quartz crystal microbalance (QCM) in association with the crystal impedance technique was used to study the viscoelastic properties of electroactive polymer films. In particular, a new analysis for the interpretation of crystal impedance data, acquired dynamically during the deposition of polyvinylferrocene (PVF) and polybithiophene (PBT), was developed and applied.;Qualitatively, the raw crystal impedance data gave information on the departure from rigidity. However, for a quantitative analysis, equivalent circuit modelling was employed. The modified Butterworth Van-Dyke lumped-element equivalent circuit model was used to extract inductive and resistive components that relate to film mass and energy loss (diagnostic for film (non)-rigidity), respectively, during deposition.;A new equivalent circuit fitting routine was developed that described the physical characteristics of polymer films in solution in terms of the complex shear moduli, G' (energy storage) and G'' (energy loss) of the film. The model consists of three components that take into account the viscoelastic polymer film, the deposition solution and the surface roughness features of the QCM.;For PVF and PBT deposition, it was found that the shear modulus was a function of film thickness and had limiting values of G' G'' 108-109 and G' G'' 106-107 dyne cm-2, respectively. This suggests that PBT films behave as Maxwell fluids, whereas PVF films behave as rubbery solids.