Characterization of the surface properties of polypyrrole films: Influence of electrodeposition parameters

Polypyrrole films were electrosynthesized on conductive tin oxide substrates by potentiostatic deposition in various aqueous electrolyte solutions including p-toluenesulfonate, naphthalenesulfate, nitrate, tetrafluoroborate, and perchlorate anions. Electrical and structural characteristics (morphology, roughness and thickness) were determined using Van der Pauw method, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Optical Profilometry (OP). Experimental parameters including the electrolyte, applied electrodeposition potential, and pyrrole concentration were shown to affect the morphologies and conductivities of so-prepared polypyrrole films. The p-toluenesulfonate doped polypyrrole film showed the highest conductivity whereas the perchlorate doped one showed the lowest conductivity of all the films. On the contrary, the film thickness did not affect the electrical conductivity. Concerning the morphology, globular-shaped topographic structures were obtained for nearly all the polymer films, but with different sizes of globules and aggregates. Both roughness and morphological features were also proved to be very dependent from the electropolymerization parameters.