Effect of synthesis parameters on the surface morphology of conducting polypyrrole films

Surface morphology of polypyrrole films was investigated by using atomic force and scanning electron microscopy techniques. Synthesis parameters such as dopant concentration and synthesis time and subsequent heat treatment were found to affect the surface morphology of electrochemically synthesized polypyrrole films. Mean height, root-mean-square roughness, and nodule diameter increased with increasing dopant concentration and synthesis time. Lightly doped, semiconducting films had smoother surface morphology with the mean height values as low as 500 Å, whereas highly doped conducting films had dendritic surfaces with the mean height values of the nodules reaching several microns. At highest dopant concentrations and/or synthesis times exceeding 2 hours the film surface no longer resembled cauliflowers but a worm-like fibrillar morphology appeared. Fibrils started growing at a dopant concentration of 0.025 M and at 0.05 M the film surface was covered with fibrils with pointed tips. Copyright © 1997 Elsevier Science Ltd.