Studies on Proton Conductivity and Methanol Permeability of Poly(ether sulfone)/Sulfonated Poly(ether ether ketone) Blen
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1098-HH03-12
Studies on Proton Conductivity and Methanol Permeability of Poly(ether sulfone)/Sulfonated Poly(ether ether ketone) Blend Membranes Hong Zhu1,2, Wein-Duo Yang3, Yong-sheng Wei2, Wu-bin Yang2, Xue-qing Yu2, and Xu-dong Cao4 1 Department of Chemistry, School of Science,Beijing University of Chemical Technology, Beijing, 100029, China, People's Republic of 2 Department of Chemistry, School of Science, Beijing Jiaotong University, Beijing, 100044, China, People's Republic of 3 Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, 807, Taiwan 4 Department of Chemical Engineering, University of Ottawa, ottawa, K1N 6N5, Canada ABSTRACT Partially Sulfonated Poly(ether ether ketone) (SPEEK) samples were prepared by modification of corresponding poly(ether ether ketone) (PEEK) with concentrated sulfuric acid. Poly(ether sulfone)(PES) was blended into SPEEK to prepare PES/SPEEK blend membranes by solution casting. The glass transition temperature of blend membranes indicated the molecular miscibility between PES and SPEEK. Characteristics of the blend membranes, including water uptake, thermal stability, methanol permeability, swelling degree, proton conductivity, etc, were investigated. PES played an important role in the blend membranes. Though the proton conductivity of PES/SPEEK blend membranes decreased to some extent, their performance for barrier methanol and swelling had remarkably enhanced, showing the feasibility for direct methanol fuel cell. Keywords: Blend membranes; Poly(ether sulfone); methanol permeability; Proton Conductivity INTRODUCTION Direct methanol fuel cells (DMFCs) have attracted considerable attention as candidates for portable power sources, because they offer the advantages of high efficiency, simple design and nearly zero emissions to environment[1,2]. The proton exchange membrane (PEM), which transfers protons from anode to cathode and acts as a barrier to avoid the crossover of fuel, is a key part of proton exchange membrane fuel cells (PEMFCs). Nafion® (DuPont) is a kind of perfluorinated ion-exchange polymer. One of its major applications is as PEMs in fuel cells due to its excellent chemical stability and high proton conductivity[3-6]. But Nafion® membranes are not suitable for DMFCs due to their high methanol permeability as well as high cost. In DMFC system, the lower methanol cross-over is important due to the diffusion of methanol through the membrane, which leads to the reduction of efficiency of fuel cells. Therefore, the ideal PEM for DMFCs should be a membrane with high conductivity, low methanol permeability and low cost[5-9]. These have motivated great efforts in developing cost-effective non-fluorinated polymer based PEMs with low methanol permeability. In recent years, several alternative PEMs have been
studied in relation to DMFCs, such as acid doped poly(N-ethylbenzimidazole) and poly(N-methylbenzimidazole)[10], sulfonated poly(styrene–isobutylene–styrene)[11], crosslinked poly(vinyl alcohol) containing sul
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