Modeling of Growth Morphology of Underpotential Electropolymerization of Pyrrole on Graphite

Recent work has revealed that nanostructured polypyrrole can be prepared electrochemically by an underpotential process on graphite. Potential step experiments using this process are characterized by geometrically increasing current. We have preferred to view data from the experiments in log-log format, plotting current vs. total charge passed during the process. This report is an effort to model the relationship between the morphology of polymer growth and the limiting slopes found in the log-log plots. We find that, regardless of the growth morphology, shape- (or aspect-) preserving growth in n dimensions is characterized by a slope of n-1/n.