New Polymer Structures for Anion Exchange Membranes

New membranes for alkaline fuel cells and other ion transport applications continue to generate a lot of interest in the electrochemical community.  Over the last 10 years there has been great progress in determining the key attributes of anion exchange membranes that lead to high fuel cell performance and moderate lifetime devices.  A current limitation of the field is the lack of readily available membranes and ionomer solutions.  Scalable, inexpensive materials are needed to promote more studies of electrode fabrication, device operation, and optimization, particularly in the area of longevity.

Our group has demonstrated a number of new polymer structures based on commercially-available polymers and inexpensive modification reagents.  We have focused on poly(phenylene oxide) as a backbone platform and employed ammonium cations that have relatively good stability in light of their low cost and reasonable performance.  In previous work, we employed alkyl chains to cause phase separation in random copolymers.  This phase separation increased the conductivity and decreased the water uptake of the materials.  We have since continued to investigate crosslinking and interpenetrating networks as further methods to optimize the properties of anion exchange membranes.  Many of these polymers have shown reasonable performance in anion exchange membrane devices, but more work is required to extend the lifetimes of the cells beyond 1000 hours.

This talk will highlight our recent work on new polymer structures and demonstrate how stability and conductivity can be increased by iterating on quaternary ammonium poly(phenylene oxide)-based materials.