Synthesis and properties of stretched polytetrafluoroethylene–sulfonated polystyrene nanocomposite membranes

• Novel PEMs based on the stretched PTFE films and sulfonated PS were obtained.
• High specific proton conductivity of the membranes up to 0.25 S cm− 1 was reached.
• Methanol permeability of the composite PEMs is 1.5 times lower than that for water.
• Performance of PEMFC based on the PEMs is 1.5-fold higher than that on Nafion.

Nanostructured stretched polytetrafluoroethylene–sulfonated polystyrene (strPTFE–sPS) ion-exchange membranes have been synthesized by sulfonation of the nanocomposite strPTFE-implanted PS films. The implantation of the PS (17–76 wt.%) was implemented by the thermal polymerization of styrene, which was absorbed from a styrene–divinylbenzene–toluene solution in the stretched PTFE film at 90 °C. The exchange capacity of the strPTFE–sPS membranes reaches 2.3 mmol g− 1. The proton conductivity of the water-saturated samples was 2–2.5 times higher than that of Nafion-115 and MF-4SC. It is found that the synthesized membranes have a methanol diffusion coefficient and permeability that are 1.5 times lower than those for water. Comparative laboratory tests in a hydrogen-air fuel cell at room temperature showed that the current–voltage and power characteristics of the cell with the strPTFE–sPS membrane substantially exceed those with the Nafion-115 membrane.