物理化学学报 >> 2016, Vol. 32 >> Issue (7): 1649-1657.doi: 10.3866/PKU.WHXB2016032804

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耗散粒子动力学模拟Nafion-[Bmim][TfO]离子液体复合膜的介观结构

麦俊林,孙德林,全学波,李理波,周健*()   

  • 收稿日期:2016-01-28 发布日期:2016-07-08
  • 通讯作者: 周健 E-mail:jianzhou@scut.edu.cn

Mesoscopic Structure of Nafion-Ionic Liquid Membrane Using Dissipative Particle Dynamics Simulations

Jun-Lin MAI,De-Lin SUN,Xue-Bo QUAN,Li-Bo LI,Jian ZHOU*()   

  • Received:2016-01-28 Published:2016-07-08
  • Contact: Jian ZHOU E-mail:jianzhou@scut.edu.cn

摘要:

采用耗散粒子动力学方法模拟研究了离子液体的含量和温度对Nafion-[Bmim][TfO]离子液体复合膜的介观结构的影响。模拟发现了微相分离现象。对不同条件下的微相分离形成的孔径分析表明,随着离子液体在复合膜中含量的增加,离子液体在膜中的聚集状态由分散的团簇转变为连续的通道,但过高的含量会产生腔室结构。随着温度的上升,离子液体通道的结构变得更加复杂,原有的腔室结构转化为通道的新支路,即高温下离子液体通道变得更加连通。界面分布几率和径向分布函数的计算结果表明,离子液体的阳离子烷基链嵌进Nafion主链中,侧链磺酸基团分布的变化直接影响咪唑基团和阴离子在微相界面的分布。本工作在介观水平上探索了Nafion-离子液体复合膜结构,可为开发高温聚电解质燃料电池材料提供一定的参考。

关键词: 燃料电池, 聚电解质, 离子液体, 耗散粒子动力学, 介观结构, 微相分离

Abstract:

The mesoscopic structure of Nafion-[Bmim][TfO] ionic liquid (IL) composite membrane was studied using dissipative particle dynamics (DPD) simulations. The effects of temperature and IL concentration on the mesoscopic structure were investigated. Microphase-separation phenomena were observed. Analyses of the pore size distributions under different conditions indicated that with the increasing IL concentration in composite membrane, the aggregated state was transformed from dispersed IL clusters to coherent IL channels. A chamber structure was formed when the IL concentration was very high. The structure of ionic liquid channels became more complex with increasing temperature and the chamber was transformed into new branches of channels, indicating that the IL channels became more coherent at elevated temperatures. The interfacial distribution probabilities and radial distribution functions indicated that the alkyl chains of ionic liquids were embedded in the Nafion backbone, and changes in the distribution of sulfonic acid groups in the side chains directly affected the distribution of imidazole groups and anions at the microphase interface. In this work, the mesoscopic structures of Nafion-IL composite membrane at the molecular level were explored and valuable insights for developing new high-temperature proton-conducting polyelectrolyte materials were obtained.

Key words: Fuel cell, Polyelectrolyte, Ionic liquid, Dissipative particle dynamics, Mesoscopic structure, Microphase separation

MSC2000: 

  • O641