Preparation and properties of cross-linked sulfonated poly(imide-siloxane) for polymer electrolyte fuel cell application

Cross-linked sulfonated poly(imide-siloxane) (cSPI-SX) is obtained by radical polymerization onto the silylmethyl group of poly(dimethylsiloxane) (PDMS). The chemical structure of the cSPI-SX thus formed is characterized by FT-IR and 13C NMR. The properties required for a proton exchange membrane, such as ion exchange capacity, water uptake, dimensional change, hydrolytic stability, and proton conductivity, are measured and investigated in detail. A transmission electron microscopic (TEM) image shows the presence of large, well-connected hydrophilic domains that are responsible for the high proton conductivity of the cSPI-SX membrane. The unique phase separated morphology of the cSPI-SX membrane supports the outstanding hydrolytic stability. A PEFC assembled with the cSPI-SX membrane has showed high power output at a humidifier gas temperature of 30 °C, a cell operating temperature of 70 °C and a gas pressure of 0.3 MPa.

► The cSPI-SX is obtained by radical polymerization onto the silylmethyl group of PDMS. ► The unique phase separated morphology of cSPI-SX supports the hydrolytic stability. ► The PEFC assembled with cSPI-SX membrane has showed high power output.