Effects of hydration level, temperature, side chain and backbone flexibility of the polymer on the proton transfer in short-side-chain perfluorosulfonic acid membranes at low humidity conditions
Effects of hydration level, temperature, side chain and backbone flexibility of the polymer on the proton transfer in short-side-chain perfluorosulfonic acid membranes at low humidity conditions
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DOI：
10.1016/j.memsci.2010.12.011
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发表时间：
2011-03-01
影响因子：
9.5
通讯作者：
Kawazoe, Yoshiyuki
中科院分区：
文献类型：
--
作者：
Ahadian, Samad;Mizuseki, Hiroshi;Kawazoe, Yoshiyuki
采用从头算分子动力学（MD）方法研究了低湿度条件下短侧链全氟磺酸（SSC PFSA）膜的电子结构性质。人工神经网络（ANN）的方法沿着与统计方法，然后建模和分析这些属性。人工神经网络方法大大加快了从头计算的电子结构计算，并具有上级精度在模仿这样的计算结果。本研究的目的是了解水化水平，温度，侧链的灵活性的SSC PFSA膜，和骨干的灵活性的SSC PFSA膜上的质子转移在这些膜的影响。使用平均值分析（ANOM）和方差分析（ANOVA）方法的统计分析结果表明，没有质子转移从SSC PFSA到邻近的水分子发生在相当低的水合水平。然而，当SSC PFSA膜充分饱和时，观察到质子转移的概率增加。该过程在低温下更有利。此外，SSC PFSA膜的侧链或主链的柔性对质子转移现象具有很大的影响，使得允许它们自由移动导致SSC PFSA膜与水分子共享其质子的亲和力增加。进一步研究了独立参数的组合效应（即，水化水平、温度、SSC PFSA膜的侧链柔性和SSC PFSA膜的主链柔性）对质子转移过程的影响，并详细报道了结果。(C)2010 Elsevier B.V.保留所有权利。
Ab initio molecular dynamics (MD) simulations are done to elucidate the electronic structure properties of a short-side-chain perfluorosulfonic acid (SSC PFSA) membrane at low humidity conditions. The artificial neural network (ANN) approach along with statistical methods is then employed to model and analyze these properties. The ANN method substantially speeds up the ab initio electronic structure calculations and has superior accuracy in mimicking the results of such calculations. The aim of this study is to understand the effects of hydration level, temperature, side chain flexibility of the SSC PFSA membranes, and backbone flexibility of the SSC PFSA membranes on the proton transfer in these membranes. Statistical analysis of results using analysis of means (ANOM) and analysis of variance (ANOVA) methods shows that no proton transfer from the SSC PFSA to the neighboring water molecules occurs at considerably low hydration levels. However, an increase in the probability of proton transfer is observed when the SSC PFSA membrane is sufficiently saturated. This process is more favorable at low temperatures. Moreover, the flexibility of either the side chains or the backbone of the SSC PFSA membrane has a great influence on the proton transfer phenomenon in such a way that allowing them to move freely causes an increase in the affinity of the SSC PFSA membrane to share its protons with water molecules. Further investigation is performed concerning the combined effect of the independent parameters (i.e., hydration level, temperature, side chain flexibility of the SSC PFSA membrane, and backbone flexibility of the SSC PFSA membrane) on the proton transfer process and the results are reported in detail. (C) 2010 Elsevier B.V. All rights reserved.