Thermally Processible AEMs from Stereospecific Polypropylene

Currently there are several anion exchange membranes that have been developed for commercial use that have demonstrated high performance and durability. However, all the membranes that are currently available are not thermally processible, like perfluorinated membrane are for proton exchange membrane devices, therefore MEA fabrication is more laborious and not currently scalable and the MEAs fabricated from the commercial polymers don’t have the same intimate contact between the membrane and catalyst layers as perfluornated membranes. The decreased contact tends to lead to lower performance, durability and the necessity of supporting electrolyte i.e., KOH. The proposed research will address this situation through the development of thermally processible stereospecific polypropylene-based anion exchange membranes. Such membrane will retain the all hydrocarbon backbone and functionality observed in current membrane systems thereby imparting similar to improved chemical durability. In addition to the chemical durability, the developed membranes will have a high ion exchange capacity to ensure competitive hydroxide conductivity and performance. Furthermore, the semi-crystalline structure combined with woven PEEK mesh support with provide excellent water management and control over swelling. Ultimately, the materials developed will provide a pathway for less expensive and commercially scalable membrane electrode assembly (MEA) fabrication. During the course of research for phase I of the proposed research we expect several accomplishments. It is expected that we will produce iso and syndiotactic polypropylene-based copolymers that will be either random or block in architecture. Such polymers, post functionalization, will have and ion exchange capacity > 2 meq/g and hydroxide conductivity >100 mS/cm. Furthermore, the AEMs fabricated from such materials will be thermally processed to fabricate MEAs that will be utilized in single cell alkaline exchange membrane water electrolysis evaluations which will show operation at 1.75V achieving >1 A/cm2. The anticipated benefits from our proposed alkaline exchange membrane development will include less expensive alkaline exchange membrane water electrolyzers to contribute to lowering the cost of green hydrogen to = $1 per kg. Furthermore, the membrane will have applications in alkaline fuel cells, carbon capture, green chemical synthesis and water desalination. Lastly, this system will enable the technologies listed to utilize platinum group metal free electrodes and eliminate the use of perfluoroalkyl substances (PFAS) from membrane production.