Wen Sheng

Properties of SPES/AlOOH Composite Proton Exchange Membranes

Novel sulfonated polyether sulfone (SPES)/AlOOH organic/inorganic composite membranes were prepared by doping SPES with AlOOH, which lowered the methanol crossover and increased the proton conductivity at high temperatures. The structure and performance of the obtained membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) etc. Compared with the pure SPES membrane the composite membranes had higher thermal stability and water uptake. The morphology of the composite membranes indicated that AlOOH was uniformly distributed throughout the SPES matrix. The network-like structure began to form when the AlOOH content was around 10%. The proton conductivity was still ca 0.014 S·cm - 1

Preparation and Properties of Sulfonated Poly(ether sulfone)/Boron Phosphate Composite Proton Exchange Membranes

Sulfonated poly(ether sulfone)(SPES)/boron phosphate(BPO4) composite membranes for application in high temperature proton exchange membrane fuel cells(PEMFCs) were successfully prepared by the sol-gel technique.The structure and performance of the obtained membranes were characterized by thermogravimetric analysis(TGA)-Fourier transform infrared(FTIR) spectroscopy,differential scanning calorimetry(DSC),and scanning electron microscopy(SEM).Results showed that the composite membranes had higher thermal stabilities and glass transition temperatures(Tg),less swelling and excellent oxidative stability.The morphology of the composite membranes indicated that BPO4 particles were uniformly distributed throughout the SPES matrix,which may facilitate proton transport.Proton conductivities of composite membranes increased as BPO4 content increased.SPES/BPO4 composite membranes showed good proton conductivities up to and above 120 ℃.SPES/BPO4 composite membranes are promising materials for possible use in PEMFCs,especially for high-temperature applications.

Preparation and Performances of Sulfonated Poly(ether imide) and Poly (ether sulfone) Blends for Proton Exchange Membrane

Sulfonated poly(ether imide) (SPEI) and poly(ether sulfone) (PES) blend membranes for application in the direct methanol fuel cells (DMFC) were successfully prepared by solution blend technique. The structure and performance of the obtained blend membranes were characterized using TGA, AFM, and SEM. The results showed that the blend membranes had higher thermal stability, lower swelling property, and good mechanical strength both in dry and wet states at ambient conditions. The morphology of blend membranes showed that its structure became more compact than that of pure SPEI, which might lead to decrease the methanol diffusion. The proton conductivity and the methanol permeability were determined by A.C. impedance spectrometry and diaphragm diffusion, respectively. The results showed that the SPEI/PES (mass ratio of 50/50) membrane still exhibited adequate conductivity (5.5 mS·cm-1) for application as proton exchange membranes. Meanwhile, the methanol permeability of the blend membranes decreased dramatically and was only 5% of that of Nafion 112 membrane. This tremendous reduction of methanol crossover could indicate a potential feasibility as a promising electrolyte for DMFC.