Synthesis and characterization of sulfonated poly(ether sulfone)s containing DHTPE for PEMFC

Sulfonated poly(ethersulfone)s (S-PDHTPEs) were prepared from DHTPE (4,4-(2,2-diphenylethenylidene)bisphenol), 4,4-sulfonyldiphenol, 4-fluorophenylsulfone using potassium carbonate, and followed sulfonation reaction with conc. sulfuric acid. DHTPE is a conjugated structure, which enables to form planar conformation between aromatic rings, and selectively sulfonated on phenyl rings of polymer side chain. A series of membranes were studied by 1H-NMR spectroscopy and thermo gravimetric analysis (TGA). The ion exchange capacity (IEC) and proton conductivity of S-PDHTPEs were evaluated with increase of degree of sulfonation. The water uptake of synthesized S-PDHTPE membranes exhibit 32–69% compared with 28% of Nafion 211. The S-PDHTPE membranes exhibit proton conductivities (80°C, RH100) of 43.1–103.2mS/cm compared with 137.4mS/cm of Nafion 211. Under a H2/O2 system, the cells with MEA made by S-PDHTPE 40 provided the maximum cell performance of around 0.32, 0.36, and 0.42, and resulting in lower than Nafion 211 of 0.45W/cm2. ► We synthesize sulfonated poly(ethersulfone)s which form conjugated planar conformation. ► We control selectively sulfonation on phenyl ring of polymer side chain. ► Increasing sulfonic group increase proton conductivity. ► Polymer membrane of 50% sulfonation exhibits similar cell performance to Nafion.