Coarse-grained hybrid Monte Carlo/molecular dynamics simulations of the nanophase separated morphology of polysulfone grafted with phosphonated sidechain for proton exchange membrane fuel cells
Coarse-grained hybrid Monte Carlo/molecular dynamics simulations of the nanophase separated morphology of polysulfone grafted with phosphonated sidechain for proton exchange membrane fuel cells
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DOI：
10.1016/j.ijhydene.2021.05.120
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发表时间：
2021-06
影响因子：
7.2
通讯作者：
Dongqing Zhang;Liuming Yan;B. Yue;Yidong Hu;Wang Zhaomin;Weimiao Lv;Hui Wang
中科院分区：
文献类型：
--
作者：
Dongqing Zhang;Liuming Yan;B. Yue;Yidong Hu;Wang Zhaomin;Weimiao Lv;Hui Wang
纳米相分离结构是一种被广泛接受的质子交换膜的质子传导性和完整性的平衡燃料电池（PEMFC）的设计。由于粗粒模拟超越了原子模拟的时空尺度，而蒙特卡罗模拟克服了分子动力学模拟在高分子链重排过程中所面临的空间位阻，因此，粗粒混合蒙特卡罗/分子动力学模拟可以有效地搜索构型空间，并可应用于质子交换膜纳米相分离形态的研究。采用CG混合MC/MD方法研究了聚乙烯基膦酸接枝聚砜（PSU-g-PVPA）质子交换膜的形态特征，并采用基于距离的聚类算法对其进行了分析。结果表明，PVPA亲水侧链和PSU疏水主链分别分离成亲水/疏水簇，导致水合后的纳米相分离形态。可以得出结论，PVPA侧链的5个重复单元的长度是必要的亲水/疏水纳米相分离，和亲水簇连接成连续的通道长距离运输质子。最后，随着PVPA侧链长度从1增加到5和10，四个最大亲水簇中的有效局部水合度（λ i/λ 0）被评估为从42.2%增加到48.0%和48.7%。
Nanophase separated morphology is a widely accepted design for the balance of proton conductivity and integrity of proton exchange membrane for fuel cells (PEMFC). Since the coarse-grained (CG) modeling goes beyond the time-and space-scales accessible to the atomistic modeling and the Monte Carlo simulation (MC) overcomes the steric hindrance that molecular dynamics simulation (MD) faces during the rearrangements of polymeric chains, the CG hybrid MC/MD searches effectively the configurational space and can be applied to the investigation of nanophase separated morphology of proton exchange membrane. In this work, the morphological characteristics of proton exchange membrane of poly (vinyl phosphonic acid) grafted polysulfone (PSU-g-PVPA) are studied using CG hybrid MC/MD and analyzed using distance-based clustering algorithm. It is revealed that the PVPA hydrophilic sidechains and the PSU hydrophobic mainchains segregate, respectively, into hydrophilic/hydrophobic clusters resulting nanophase separated morphology upon hydration. It is concluded that a length of five repeat units for the PVPA sidechains is necessary for the hydrophilic/hydrophobic nanophase separation, and the hydrophilic clusters connect into continuous channels for the long-distance transport of protons. Finally, the effective local hydration degrees (λ i/λ 0) in the four largest hydrophilic clusters are evaluated to increase from 42.2% to 48.0% and 48.7% as the PVPA sidechain length increases from 1 to 5 and 10.