Structurally Well-Defined Anion-Exchange Membranes Containing Perfluoroalkyl and Ammonium-Functionalized Fluorenyl Groups
Structurally Well-Defined Anion-Exchange Membranes Containing Perfluoroalkyl and Ammonium-Functionalized Fluorenyl Groups
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DOI：
10.1021/acsomega.8b02742
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发表时间：
2018-11
期刊：
影响因子：
4.1
通讯作者：
Mizuki Ozawa;Taro Kimura;Kanji Otsuji;R. Akiyama;J. Miyake;M. Uchida;J. Inukai;K. Miyatake
中科院分区：
文献类型：
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作者：
Mizuki Ozawa;Taro Kimura;Kanji Otsuji;R. Akiyama;J. Miyake;M. Uchida;J. Inukai;K. Miyatake
合成并表征了含全氟烷基和铵官能化芴基团的新型阴离子导电聚合物。使用二甲基胺化芴单体合成的季铵化聚合物具有明确定义的化学结构，其中每个芴基在特定位置被两个铵基取代。所得聚合物具有高分子量（Mn = 8.9- 13.8kDa，Mw = 13.7- 24.5kDa），以通过溶液浇铸提供具有0.7至1.9毫当量g-1的离子交换容量（IEC）的可弯曲薄膜。透射电子显微镜图像和小角X-射线散射图案表明，聚合物膜具有纳米级的相分离的形态的基础上的聚合物组分中的亲水/疏水的差异。与文献中发现的典型阴离子交换膜不同，膜的氢氧根离子电导率不随IEC的增加而增加，因为它们在水中的高溶胀能力。具有IEC = 1.2 mequiv g-1的膜显示出高氢氧根离子电导率（在80 ℃下在水中为81 mS cm-1）和机械强度（在80 ℃、60%相对湿度下>100%伸长率和14 MPa最大应力）的平衡性质。聚合物主链在4 M KOH中稳定1000 h，而三甲基苄基型铵基团在导致氢氧根离子电导率损失的条件下降解。具有IEC = 1.2 mequiv g-1的膜的H2/O2燃料电池在580 mA cm-2电流密度下表现出242 mW cm-2的最大功率密度。
Novel anion-conductive polymers containing perfluoroalkyl and ammonium-functionalized fluorene groups were synthesized and characterized. The quaternized polymers synthesized using a dimethylaminated fluorene monomer had a well-defined chemical structure in which each fluorenyl group was substituted with two ammonium groups at specific positions. The resulting polymers had a high molecular weight (Mn = 8.9–13.8 kDa, Mw = 13.7–24.5 kDa) to provide bendable thin membranes with the ion-exchange capacity (IEC) ranging from 0.7 to 1.9 mequiv g–1 by solution casting. Both transmission electron microscopy images and small-angle X-ray scattering patterns suggested that the polymer membranes possessed a nanoscale phase-separated morphology based on the hydrophilic/hydrophobic differences in the polymer components. Unlike typical anion-exchange membranes found in the literature, hydroxide ion conductivity of the membranes did not increase with increasing IEC because of their high swelling capability in water. The membrane with IEC = 1.2 mequiv g–1 showed balanced properties of high hydroxide ion conductivity (81 mS cm–1 at 80 °C in water) and mechanical strength (>100% elongation and 14 MPa maximum stress at 80 °C, 60% relative humidity). The polymer main chains were stable in 4 M KOH for 1000 h, whereas the trimethylbenzyl-type ammonium groups degraded under the conditions to cause loss in the hydroxide ion conductivity. An H2/O2 fuel cell with the membrane with IEC = 1.2 mequiv g–1 exhibited a maximum power density of 242 mW cm–2 at 580 mA cm–2 current density.