Local structure and hydrogen bond characteristics of imidazole molecules for proton conduction in acid and base proton-conducting composite materials
Local structure and hydrogen bond characteristics of imidazole molecules for proton conduction in acid and base proton-conducting composite materials
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DOI：
10.1039/c7cp08396c
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发表时间：
2018-04-21
影响因子：
3.3
通讯作者：
Mizuno, Motohiro
中科院分区：
文献类型：
--
作者：
Hori, Yuta;Chikai, Takuma;Mizuno, Motohiro
酸性聚合物与碱性分子的复合材料具有高质子传导性。了解复合材料取决于氢键特性的质子传导机制是开发高质子传导率材料的重要任务。本工作以聚（乙烯基膦酸）-咪唑和海藻酸-咪唑作为酸性聚合物与碱性分子的复合材料为例，利用密度泛函理论研究了复合材料中咪唑（Im）分子的局域结构和氢键特征。结果表明，Im分子与这些复合材料中的聚合酸发生强烈相互作用，并且相互作用能随着Im分子数量的增加而增加。 Im 分子的旋转运动发生在只有没有多余质子的 Im 分子彼此形成氢键的部分。取决于氢键环境的各个段的计算结果表明，复合材料中的质子传导过程由以下步骤组成：Im分子与聚合酸相互作用的段中的质子转移，Im分子受到过量质子影响的段中的质子转移，以及只有没有过量质子的Im分子相互键合的段中Im分子重新取向的Grotthuss扩散。
Composite materials of acidic polymers and basic molecules have high proton-conductivity. Understanding the proton conduction mechanism of the composite materials, which depends on hydrogen bond characteristics, is an important task for developing materials with high proton-conductivity. This work is focused on poly(vinylphosphonic acid)-imidazole and alginic acid-imidazole as examples of composite materials of acidic polymers and basic molecules and examines the local structure and hydrogen bond characteristics of imidazole (Im) molecules in composite materials using density functional theory. The results show that Im molecules interact strongly with polymeric acids in these composite materials and that the interaction energy increases with the increase in the number of Im molecules. The rotational motion of Im molecules occurs in the segment where only Im molecules without excess protons are hydrogen-bonded to each other. The calculation results for the various segments, which depend on the hydrogen bonding environment, show that the proton conduction process in composite materials consists of the following steps: proton transfer in the segment where Im molecules interact with polymeric acids, proton transfer in the segment where Im molecules are affected by excess protons, and Grotthuss diffusion with reorientation of Im molecules in the segment where only Im molecules without excess protons are bonded to each other.