A comparison of fracture and permanganic etching of polypyrrole films

The internal organization within electrochemically polymerized films of the conducting polymers polypyrrole p-toluene sulphonate and polypyrrole sulphate has been examined by scanning electron microscopy (SEM) following transverse fracture and permanganic etching of microtomed cross sections. X-ray scattering studies have shown these two materials to exhibit very different internal ordering: polypyrrole-p-toluene sulphonate is thought as being anisotropic, with the counter ions and polypyrrole chains lying down preferentially in the plane of the work electrode, whereas polypyrrole sulphate is considered to be isotropic. Comparison of the internal textures following the two different preparative techniques shows significant differences. Whereas the morphology revealed in transverse fracture surfaces correlates closely with x-ray scattering data, etched surfaces exhibit a morphology that is in good agreement with the direct examination of sections prepared by ultramicrotomy. Despite the apparent contradiction in these two sets of data, a consistent picture of the true morphology (as revealed by permanganic etching) can be deduced and reconciled with the fracture surface micrographs. (C) 1996 John Wiley & Sons, Inc.