Atomic force microscopy study of conducting polymer films near electrode's edge or grown on microband electrode

Polypyrrole (PPy) films of different thicknesses (within the range from 200 nm to 2.5 μm) were electrodeposited on two types of inhomogeneous substrates, single band and double-band Pt electrodes. Topographic images of the polymer layers were obtained by means of ex situ large-scale AFM technique to demonstrate how the propagation rates of the film growth above the electrode (in the normal direction to the electrode surface) and along the insulating surface surrounding the single- or double-band electrodes (in the horizontal direction) change with the deposition charge. It is proved that variations in the film thickness over the double band electrodes and progressive changes of the PPy morphology from compact thin film to rough thick layers represents an obstacle for reliable determination of the specific conductivity of the deposited polymer film from conductance/resistance data for such coated microband electrodes. Advantages and shortcomings of other methods of specific conductivity measurements of the polymer films are also discussed.