| Summary: | 碩士 === 元智大學 === 化學工程與材料科學學系 === 97 === Composite proton exchange membranes were prepared from sulfonated poly (phthalazinone ether ketone) (sPPEK) and various amounts of sulfonated polyhedral oligosilsesquioxane (sPOSS). The composite membranes were prepared by casting method with the sulfonated POSS (sPOSS) mixed in sPPEK solution. The chemical structure of the sPOSS was confirmed by FTIR and the degree of sulfonation was identified as 7 % by sulfur content and ion exchange capacity. The membranes were evaluated in terms of thermal stability, water uptake, methanol solution (3M) uptake, bound water ratio, proton conductivity, methanol permeability, and single cell performance. When the degree of sulfonation of sulfonated PPEK was higher, the membrane had higher degree of swilling, but the composite membrane could maintain good dimentional stability. At 80 °C, the water uptake of composite membrane was lower than the original membrane, because the interaction between -SO3H and -OH group decreased the mobility of molecule chains.. The composite membrane contained 5 % sPOSS exhibited the highest proton conductivity of 2.6×10-2 S/cm at 90 °C and 95 % relative humidity, because the sPOSS provide more sulfonic acid group to make more pathway for proton. The composite membranes with various sPOSS content showed lower methanol permeability than the cast Nafion membrane, possibly due to a winding pathway by adding sPOSS for methanol diffusion. The composite 5 % sPOSS/sPPEK membrane showed the highest current density (253mA/cm2) and power density (32 mW/cm2) among all the membranes tested with 3 M methanol in feed at 70 oC.
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