Molecular structure and dynamics of lithium perchlorate + 18-crown-6 macrocyclic complexes in dimethylcarbonate at 25.degree.C

Abstract

required before we can definitely say that the difference is due to the mobility of the cation in the film. We are currenly repeating the current-pulse experiment using Bu4NBF4 as the supporting electrolyte.The apparent diffusion coefficients obtained from the finite diffusion regime are consistently larger than the £>app's from the semiinfinite regime (Table II). Rubinstein et al. applied the method described here to an electrode coated with a redox polymer film and noted a similar discrepancy; however, in their case Z>apPiF was a factor of 3 less than Dappj.20a Rubinstein et al. account for this observation by postulating the existence of two uncoupled diffusion pathways within the polymer film.208 This explanation could, in principle, account for the trend in the data observed here.Electron micrographs of electrochemically synthesized polypyrrole clearly show that the polypyrrole surface is not smooth.268,31 if the surface topological features are significant relative to the average film thickness, the film will clearly not be of uniform thickness. Furthermore, because the profilometer stylus is too large to fit into the crevices between surface topological features, the thickness measured is probably the maximum thickness (i.e., the locus of points most distant from the substrate Pt electrode surface). Because Z)app-F is proportional to l2, this overestimated