Tröger's Base Polymer Blended with Poly(Ether Ketone Cardo) for High Temperature Proton Exchange Membrane Fuel Cell Applications

Developing membrane electrolyte materials with high performance and low cost is a key factor in promoting the application and commercialization of the high temperature proton exchange fuel cell (HT-PEMFC). In this work, a Tröger’s base (TB) polymer of DMBP-TB is synthesized from commercially available and low-cost 4,4’-diamine-3,3’-dimethyl-biphenyl (DMBP) and dimethoxy methane in trifluoroacetic acid via a one-pot TB polymerization reaction under mild conditions. The obtained DMBP-TB polymer occupies a good organic solubility, high thermal stability and excellent chemical resistance. Due to the in-built bicyclic amine rings and intrinsic microporosity structure, the pure DMBP-TB membrane exhibits a remarkable phosphoric acid (PA) doping content as high as 1205% in 85 wt% PA solution at room temperature. However, the excessive swelling and poor mechanical integrity hinder the PA doped DMBP-TB membrane as the HT-PEM. Thus, the commercial and low-cost engineering thermoplastic of poly(ether ketone cardo) (PEKC) is employed as the enhanced material to prepare DMBP-TB blend membranes. The DMBP-TB/50%PEKC/149%PA membranes displays an anhydrous conductivity of 0.061 S cm-1 at 180 °C and a tensile strength of 8.7 MPa at room temperature, which enables H2-O2 fuel cell with a peak power density of 536 mW cm-2 at 180 °C without backpressure, suggesting the utility for HT-PEMFCs