| Abstract
| - A simple voltammetric procedure for measuring the kinetics of slow partitioning processes into thin films isdescribed and applied to determine the transport of trimethylammonium ferrocinium, FA+, into ultrathin NafionLangmuir−Schaefer films. By recording cyclic voltammograms for the oxidation of FA+ as a function oftime of a Nafion modified electrode placed in a dilute solution containing FA+, one can readily measure theuptake of FA+ into a film. An analytical model for the charge accumulated in the film has been derived forthe cases of (i) transport-controlled partitioning; (ii) transport with a kinetic barrier at the film/solution (f/s)interface; and (iii) pure kinetic control. Analysis of experimental data indicates that, in contrast to dropcastNafion films, there is a significant kinetic barrier at the f/s interface to FA+ partitioning. The methodologyand theory described are generic and could be applied to other chemical systems and detection methods.
|
