Highly sulfonated multiblock copoly(ether sulfone)s for fuel cell membranes
Highly sulfonated multiblock copoly(ether sulfone)s for fuel cell membranes
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DOI：
10.1002/pola.24023
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发表时间：
2010-07
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影响因子：
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通讯作者：
Kazuhiro Nakabayashi;Tomoya Higashihara;M. Ueda
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文献类型：
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作者：
Kazuhiro Nakabayashi;Tomoya Higashihara;M. Ueda
通过相应的羟基封端低聚物在高活性十氟联苯（DFB）作为扩链剂的存在下进行偶联反应，然后用浓硫酸进行后磺化，合成了适用于质子电解质燃料电池（PEFC）的高度磺化的多嵌段共聚（醚砜）。通过粘度测量测定，它们的分子量相当高（η inh = 0.72-1.58 dUg）。还证实后磺化选择性地发生在亲水链段中，产生高度磺化的多嵌段共聚物（IEC = 1.90-2.75 mequiv/g）。所得聚合物通过溶液流延形成透明、柔韧且坚韧的膜。作为代表性样品，4b 膜在干燥状态下表现出良好的机械强度，无论 IEC 值如何（2.75 mequiv/g）。具有较高 IEC 值（IEC = 2.75-2.79 mequiv/g）的 4a-c 膜在 50% RH 下保持高吸水率（13.7-17.7 wt%），在 30% RH 下仍保持高吸水率（7.4-8.5 wt%）。所有膜在 80 °C 和 95% RH 下的质子电导率均高于 Nafion 117。此外，4a 膜在 50-95% RH 范围内表现出较高的质子电导率，与 Nafion 117 相当，并且即使在 30% RH 下也能保持较高的质子电导率 (2.3 x 10 -3 S/cm)。最后，通过轻敲模式原子力显微镜研究了膜的表面形态，显示出连接良好的亲水域，可以作为质子传输通道。这种相分离和高吸水行为可能有助于在较宽的相对湿度范围内实现高且有效的质子传导。
Highly sulfonated multiblock copoly(ether sulfone)s applicable to proton electrolyte fuel cells (PEFCs) were synthesized by the coupling reaction of corresponding hydroxyl-terminated oligomers in the presence of highly reactive decafluorobiphenyl (DFB) as a chain extender, followed by postsulfonation with concentrated sulfuric acid. Their molecular weights were reasonably high as determined by viscosity measurement (η inh = 0.72-1.58 dUg). It was also confirmed that postsulfonation selectively took place in hydrophilic segments to yield highly sulfonated multiblock copolymers (IEC = 1.90-2.75 mequiv/g). The resulting polymers gave transparent, flexible, and tough membranes by solution casting. The 4b membrane, as a representative sample, demonstrated good mechanical strength in the dry state regardless of high IEC value (2.75 mequiv/g). The 4a-c membranes with higher IEC values (IEC = 2.75-2.79 mequiv/g) maintained high water uptake (13.7-17.7 wt %) at 50% RH and it was still high (7.4-8.5 wt %) at 30% RH. Proton conductivity of all membranes at 80 °C and 95% RH was higher than that of Nafion 117. Furthermore, the 4a membrane showed high proton conductivity, comparable with Nafion 117 in the range of 50-95% RH, and maintained high proton conductivity (2.3 x 10 -3 S/cm) even at 30% RH. Finally, the surface morphology of the membrane was investigated by tapping mode atomic force microscopy, which showed well-connected hydrophilic domains that could work as proton transportation channel. This phase separation and the high water uptake behavior probably contributed to high and effective proton conduction in a wide range of relative humidity.