Poly[3,6‐(carbaz‐9‐yl)propanesulfonate]: A Self‐Doped Polymer with Both Cation and Anion Exchange Properties

A water‐soluble, self‐doped, electroactive polymer, poly[3,6‐(carbaz‐9‐yl)propanesulfonate] (PCPS), has been prepared for the first time. Electrochemical analyses show that this polymer has two separate oxidation states involving interactions of the polymer backbone with the covalently bound, self‐doping ions and counterions from electrolyte, indicating that the polymer has the ability to act as a potential‐dependent charge‐controllable membrane with both cation‐exchange and anion‐exchange properties. We have used the quartz crystal microbalance technique to investigate these two processes, to verify the self‐doping mechanisms exhibited by PCPS, and detail the charge/mass transport relationships in this polymer.