从头算分子动力学描述季铵化SEBS阴离子交换膜中氢氧根离子的结构扩散,The Journal of Physical Chemistry C

当前位置： X-MOL 学术 › J. Phys. Chem. C › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

从头算分子动力学描述季铵化SEBS阴离子交换膜中氢氧根离子的结构扩散
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-04-09 , DOI: 10.1021/acs.jpcc.9b10018
Sergio Castañeda _{1,

1} , Rafael Ribadeneira _{1,

1}

Affiliation

氢氧根离子通过结构扩散通过官能化的聚苯乙烯嵌段-聚（乙烯-亚甲基-丁烯）嵌段的一部分进行运输使用从头算分子动力学（AIMD）在两个水合水平分析了聚苯乙烯（QSEBS）膜。首先，进行动态模拟以识别和描述关于（a）导电聚合物的水合和（b）氢氧根离子的位置和溶剂化模式的结构扩散特征。然后，估算氢氧化物的扩散率和电导率，并将其与纯水模拟结果和水合QSEBS的实验电导率数据进行比较。发现在聚合物体系中氢氧根离子的水合和位置对电荷转移事件的特征和频率有很大的影响。例如，具有高配位数或位于干燥区中的氢氧根离子是具有最低数量结构扩散事件的分子，这些事件有效地促进了氢氧根的位移（非响尾声事件）并且具有最高的平均寿命。计算得出的扩散系数和氢氧化物电导率相对于散装水中的水合和电导率显示出一致的趋势和大小。此外，模拟表明，随着水合作用的增加，非棘手电荷转移事件的数量也会增加，并且通过结构扩散也有助于氢氧化物的迁移。这不仅证实了已开发的模拟相对于文献中提出的阴离子交换膜物理模型的一致性，

"点击查看英文标题和摘要"

Description of Hydroxide Ion Structural Diffusion in a Quaternized SEBS Anion Exchange Membrane Using Ab Initio Molecular Dynamics

The transport via structural diffusion of hydroxide ions through a segment of the functionalized polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (QSEBS) membrane is analyzed at two hydration levels using ab initio molecular dynamics (AIMD). First, dynamic simulations are carried out to identify and describe the characteristics of structural diffusion with respect to (a) hydration of the conductive polymer and (b) location and solvation pattern of hydroxide ions. Then, hydroxide diffusivity and conductivity are estimated and compared with data from simulations in pure water and experimental conductivity for hydrated QSEBS. A strong influence was found of the hydration and location of hydroxide ions in the polymeric system in the characteristics and frequency of charge-transfer events. As an example of this, hydroxide ions having high coordination numbers or located in dry zones are the molecules with lowest number of structural diffusion events that contribute effectively to hydroxide displacement (nonrattling events) and have the highest mean-lifetimes. Calculated diffusion coefficients and hydroxide conductivities showed a coherent tendency and magnitude with respect to hydration and conductivity in bulk water. Also, simulations show that as hydration increases, so does the number of nonrattling charge-transfer events and contribution to hydroxide mobility by structural diffusion. This not only corroborates the consistency of the developed simulations with respect to proposed physical models for anion-exchange membranes in the literature, but also represents an important contribution to the detailed understanding of transport phenomena at the atomic scale and the role of cationic functional chains of the polymer in the development of transport mechanisms at such scale and their contribution to hydroxide mobility.

更新日期：2020-04-09

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南