On/off switching in field assisted ion transport through a polymer membrane system

In our previous work, we demonstrated ion selective transport through a single membrane. In this study, we adopted a new method by using a dual membrane system to improve the performance. Two gold-sputtered membranes were mounted between two independent glass cells. Then, polypyrrole (PPy) was electrochemically deposited on the gold side of each membrane. Benzylamine (BA) and Methylene blue (MB) were used as the probe materials in this membrane system. Since the PPy serves as a separator and an electrode, an electric field could be applied between the two membranes directly. Furthermore, a high electric field could be obtained between the two membranes even at a low applied potential because the distance between the two membranes is in microunits. As a result, the dual membrane system exhibited improved control and selectivity for the ions. Finally, the different transport mechanism for BA and MB was discussed in detail.