Cation/Anion Associations in Ionic Liquids Modulated by Hydration and Ionic Medium
Cation/Anion Associations in Ionic Liquids Modulated by Hydration and Ionic Medium
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DOI：
10.1021/jp1110899
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发表时间：
2011-04-28
影响因子：
3.3
通讯作者：
Madsen, Louis A.
中科院分区：
文献类型：
--
作者：
Hou, Jianbo;Zhang, Zhiyang;Madsen, Louis A.
为了了解离子液体独特的溶剂化和导电特性，我们研究了水化水平和离子介质对离子间缔合的调节。脉冲场梯度核磁共振允许敏感地测量分离的阳离子和阴离子扩散系数，它们结合起来反映离子聚集。随着ILs水化程度的增加，阳离子与阴离子扩散系数的异常比值发生逆转，然后趋于稳定，达到与预期水动力半径比一致的值（r（阳离子）/r（阴离子）= 1.4,[C-2 mim][BF4]）。当离子离子在离子聚合物内部扩散时，离子结合受到移动阳离子和阴离子之间的离子相互作用的调节，并从固定的-SO3中拖动聚合物的亲水通道。令人惊讶的是，阳离子扩散得更快(
In order to understand the unique solvation and conduction properties of ionic liquids (ILs), we explore their interionic associations modulated by hydration level and ionic medium. Pulsed-field-gradient NMR allows sensitive measurement of separate cation and anion diffusion coefficient, which combine to reflect ionic aggregation. With increasing hydration of ILs, the anomalous ration of cation to anion diffusion coefficients reverses, then plateaus to values consistent with expected hydrodynamic radii ratios (r(cation)/r(anion) = 1.4 for [C-2 mim][BF4]). When ILs diffuse inside an ionic polymer, ion associtions are modulated by ionic interactions between mobile cations and anions, and drag from fixed -SO3 lilning the polymer's hydrophilic channels. Surprisingly, cations diffuse substantially faster (