Fluorine-Free Precise Polymer Electrolyte for Efficient Proton Transport: Experiments and Simulations
Fluorine-Free Precise Polymer Electrolyte for Efficient Proton Transport: Experiments and Simulations
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DOI：
10.1021/acs.chemmater.1c01443
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发表时间：
2021-07-27
影响因子：
8.6
通讯作者：
Winey, Karen, I
中科院分区：
文献类型：
--
作者：
Paren, Benjamin A.;Thurston, Bryce A.;Winey, Karen, I
设计具有可控纳米形态和可伸缩合成的聚合物，对于开发燃料电池质子交换膜的无氟材料具有重要意义。本研究的重点是一种高离子交换容量(4.2 mmol/g)的高密度聚乙烯。聚合物自组装成亲水和疏水共连续的纳米结构域。在水合状态下，由极性磺酸部分和水组成的亲水结构域是有效的介观质子导电性的途径。用原位X射线散射和电化学阻抗谱技术研究了水合条件下p5PhSA的形貌和质子传输特性。在40℃和95%相对湿度下，p5PhSA的质子电导率为0.28 S/厘米，是相同条件下Nafion 117的4倍。原子分子动力学(MD)模拟也被用来解释结构和水动力学之间的相互作用。分子动力学模拟表明，在大范围的水含量范围内，渗透的亲水和疏水结构域之间有很强的纳米相分离。渗透的亲水纳米结构域促进了质子在p5PhSA中的快速传输，并展示了精确的碳氢基聚合物作为可加工和有效的质子交换膜的潜力。
Designing polymers with controlled nanoscale morphologies and scalable synthesis is of great interest in the development of fluorine-free materials for proton-exchange membranes in fuel cells. This study focuses on a precision polyethylene with phenylsulfonic acid branches at every fifth carbon, p5PhSA, with a high ion-exchange capacity (4.2 mmol/g). The polymers self-assemble into hydrophilic and hydrophobic co-continuous nanoscale domains. In the hydrated state, the hydrophilic domain, composed of polar sulfonic acid moieties and water, serves as a pathway for efficient mesoscopic proton conductivity. The morphology and proton transport of p5PhSA are evaluated under hydrated conditions using in situ X-ray scattering and electrochemical impedance spectroscopy techniques. At 40 degrees C and 95% relative humidity, the proton conductivity of p5PhSA is 0.28 S/cm, which is four times greater than Nafion 117 under the same conditions. Atomistic molecular dynamics (MD) simulations are also used to elucidate the interplay between the structure and the water dynamics. The MD simulations show strong nanophase separation between the percolated hydrophilic and hydrophobic domains over a wide range of water contents. The percolated hydrophilic nanoscale domain facilitates the rapid proton transport in p5PhSA and demonstrates the potential of precise hydrocarbon-based polymers as processible and effective protonexchange membranes.