Water Uptake and Proton Conductivity in Porous Block Copolymer Electrolyte Membranes
Water Uptake and Proton Conductivity in Porous Block Copolymer Electrolyte Membranes
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DOI：
10.1021/acs.macromol.5b00950
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发表时间：
2015-08-25
期刊：
影响因子：
5.5
通讯作者：
Balsara, Nitash P.
中科院分区：
文献类型：
--
作者：
Chen, X. Chelsea;Kortright, Jeffrey B.;Balsara, Nitash P.
我们证明了质子导电嵌段共聚物电解质膜的吸水率和电导率可以通过在导电域中引入孔来系统地控制。我们从一种由均聚聚苯乙烯（hPS）和聚苯乙烯-b-聚乙烯-b-聚苯乙烯（SES）共聚物混合物组成的膜开始。在四氢呋喃和甲醇中冲洗膜会导致hPS溶解，留下多孔膜。然后将多孔SES膜中的聚苯乙烯结构域磺化，得到具有亲水性和疏水性结构域的多孔膜。通过控制混合膜中hPS的体积分数phi(v)来控制孔隙度。采用扫描透射电镜（STEM）、电子断层扫描（electron tomography）和软x射线共振散射（RSoXS）对磺化前后膜的形貌进行了研究。磺化前后的多孔结构具有质的差异。磺化膜的吸水率随phi(v)的增加而增加。质子电导率是φ (v)的非单调函数，在φ (v) = 0.1处达到最大值。在导电域中引入微观孔隙为调整质子导电膜中的吸水和离子传输提供了额外的处理。
We demonstrate that the water uptake and conductivity of proton-conducting block copolymer electrolyte membranes can be controlled systematically by the introduction of pores in the conducting domains. We start with a membrane comprising a mixture of homopolymer polystyrene (hPS) and a polystyrene-b-polyethylene-b-polystyrene (SES) copolymer. Rinsing the membranes in tetrahydrofuran and methanol results in the dissolution of hPS, leaving behind a porous membrane. The polystyrene domains in the porous SES membranes are then sulfonated to give a porous membrane with hydrophilic and hydrophobic domains. The porosity is controlled by controlling phi(v), the volume fraction of hPS in the blended membrane. The morphology of the membranes before and after sulfonation was studied by scanning transmission electron microscopy (STEM), electron tomography, and resonance soft X-ray scattering (RSoXS). The porous structures before and after sulfonation are qualitatively different. Water uptake of the sulfonated membranes increased with increasing phi(v). Proton conductivity is a nonmonotonic function of phi(v) with a maximum at phi(v) = 0.1. The introduction of microscopic pores in the conducting domain provides an additional handle for tuning water uptake and ion transport in proton-conducting membranes.