Compositional effect on the properties of sulfonated and nonsulfonated polymer blend membranes for direct methanol fuel cell

Abstract

Various morphologies of blend membranes were prepared by changing drying condition and composition and their effect on the proton conductivity and the methanol crossover were discussed for direct methanol fuel cell. To obtain high proton conductivity but low fuel loss, highly sulfonated poly(arylene ether sulfone) (IEC=1.9 meq/g for sPAES55, synthesized with 55 mol% sulfonated monomer) was blended with nonsulfonated poly(ether sulfone) (IEC=0 meq/g for RH2000 ® , provided from Solvay) in solution blending manner. The blend ratio of sPAES55 and RH2000 was varied as 5 to 5, 6 to 4, 7 to 3, and 8 to 2 and three different temperatures (-42, -20, and 80 o C) were applied during the drying step to control the rate of phase separation. The effect of the blend ratio on the morphology, proton conductivity, and methanol permeability of the blend membrane was analyzed in combination with the drying process and finally the most desirable blend membrane for direct methanol fuel cell was proposed.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

“…The entirely hydrophobic polyethylene matrix may be also responsible for the delay of methanol permeation to some extent since the water repelling region in the membrane will not allow methanol to go through. Many researchers reported that methanol permeability and proton conductivity are proportional to IEC of PEMs [ 20 , 21 , 26 , 27 ]. In this case, the PE-g-s-PAES PEMs follows the same general trend.…”

“…Some research efforts have been made to prepare Nafion composite membranes with various inorganic materials [ 15 , 16 ]. On the other hand, many alternative polymers, including poly(arylene ether sulfone), poly(etherketone), polyimides [ 17 ], polybenzimidazole (PBI) [ 18 ], and polymer blends [ 19 , 20 , 21 , 22 ], have been studied for direct methanol fuel cells with some limited success. In these aromatic polymers, the hydroxyl (HO•) and hydroperoxyl radical (HOO•) originally formed at the anode can attack double bonds in aromatic rings, causing a ring opening or chain scission [ 9 , 10 , 11 ].…”

Synthesis and Characterization of Polyethylene-g-Sulfonated Polysulfone Copolymers for Proton Exchange Membranes

“…Howeve, it also exhibits several shortfalls that hinder its large-scale, commercial adaptation, including high cost, limited processibility, poor selectivity (methanol crossover), reduced conductivity at high temperature and low humidity conditions. As an alternative to Nafion, several sulfonated poly(arylene)-based engineering plastics, such as poly(arylene ether sulfone), poly(etherketone), and poly(etheretherketone), were extensively studied for PEMs in the past two decades (7,(9)(10)(11)(12). These polymers offer several advantages of easy processing, good thermal stability and lower manufacturing costs.…”

Synthesis of Polyethylene-Based Proton Exchange Membranes Containing PE Backbone and Sulfonated Poly(arylene ether sulfone) Side Chains for Fuel Cell Applications

“…However, Nafion also exhibits many shortfalls that hinder its large-scale, commercial adaptation, including high cost, limited processability, poor selectivity (methanol crossover), and reduced conductivity at high temperature and under low humidity conditions. As an alternative to Nafion, several sulfonated poly(arylene)-based engineering plastics, such as poly(arylene ether sulfone), poly(ether ketone), and poly(ether ether ketone), were extensively studied for PEMs in the past 2 decades. ,− These polymers offer many advantages due to ease of synthesis and fabrication, good thermal stability, high ion exchange capacity, and lower manufacturing costs. Because of the polycondensation mechanism, the synthesis requires high purity monomers with a precise functional group stoichiometry to obtain high molecular weight poly(arylene) polymers.…”