Poly(2,6-dimethyl-1,4-phenylene oxide) Based Anion Exchange Membranes for Fuel Cell Applications

Abstract

Anion exchange membranes are an integral part of a low temperature polymer electrolyte fuel cell. They serve the purpose of transporting hydroxide ions from cathode to anode while acting as a separator for fuel and air. In this work we are focused on synthesis and device testing of some novel poly(2,6-dimethyl-1,4-phenylene oxide) based AEMs. The idea is to start with a polymer that is readily available in the market and synthesize large quantities of functionalized materials. Our work centers around attaching conventional quaternary ammonium cations as well as long spacer chain quaternary ammonium cations on the polymer backbone. We solvent cast and melt press the synthesized polymer to fabricate a membrane. Melt pressing crosslinks the membrane and adds the required mechanical and dimensional stability. We are able to achieve high degree of chlorination (~80%) of polyphenyle oxide and still maintain the swelling properties of the polymer because of crosslinking. Our initial experiments show that the membrane has promising chloride conductivity, mechanical and dimensional stability thus making it suitable for fuel cell testing. We are also testing the device performance of these membranes using H2/O2fuel cell with Pt/C catalyst at various temperatures and different humidification levels to find the optimum operating conditions without causing significant degradation of the membrane. Overall we are reporting a novel AEM material with simple chemistry which can be synthesized in large batches with ease and can serve as s good fuel cell membrane in the future.