Characterization of polymer nanocomposite films using quartz thickness shear mode (TSM) acoustic wave sensor

Quartz thickness shear mode (TSM) resonator is adopted to characterize the viscoelastic properties of polymer nanocomposite thin films deposited on the resonators surface. The input electric admittance of multilayer loaded TSM acoustic wave resonator is first derived using transfer matrix method by taking into account the acoustic wave impedance of the polymeric layer. Nanocomposite thin films of multi-wall carbon nanotubes (MWCNTs) in copolymers of polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) are deposited on TSM resonators through spin-on coating processing. The electric impedance spectra of the unloaded and loaded acoustic wave resonators are measured experimentally, and a data fitting approach is applied to extract the properties of the polymer nanocomposites films. It has been found that the thickness of the polymer layer plays a very important role in the extraction of the viscoelastic properties of the films through data fitting. Viscoelastic properties of PVDF-TrFE/CNT nanocomposite thin films with CNT concentrations of 0%, 1% and 2% have been extracted by this method. The results indicate that under the current experimental conditions, for low CNT concentrations the reinforcement of the elastic shear modulus of polymer nanocomposite films is not significant.