Preparation and characterization of cross-linked polyphosphazene-crown ether membranes for alkaline fuel cells

A polymer with excellent mechanical properties and chemical properties was selected as the skeleton, and a crown ether instead of the traditional quaternary ammonium and quaternary phosphonium groups was introduced into the polymer. Three crosslinked crown ether membranes (PDB155P-HAH40, 50, and 60) with different crown ether contents were prepared and their structures and properties were characterized. The ionic conductivity of PDB155P-HAH 60 is 78.6 mS/cm at 90 °C. The degradation rates of ionic conductivity were only 2.5% and 0.99% after the membrane was soaked in 4 mol/L NaOH solution for 10 days and in 2 mol/L NaOH solution for 1000 h, respectively. The water uptake and swelling ratio of the membrane are relatively low, and the thermal stability and mechanical properties meet the requirements of the application. These membranes have great potential in the application.