A Pictorial View of Viscosity in Ionic Liquids and the Link to Nanostructural Heterogeneity
A Pictorial View of Viscosity in Ionic Liquids and the Link to Nanostructural Heterogeneity
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DOI：
10.1021/acs.jpclett.0c00170
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发表时间：
2020-03-19
影响因子：
5.7
通讯作者：
Margulis, Claudio J.
中科院分区：
文献类型：
--
作者：
Amith, Weththasinghage D.;Araque, Juan C.;Margulis, Claudio J.
原型离子液体（Ion Liquids，IL）的特征在于与（1）邻位相互作用，（2）形成正负电荷交替的链或网络，以及（3）这些网络与非极性结构域的交替相关的三个结构基序。在最近的文章中，我们强调了这些系统中的摩擦和流动性在空间上是不均匀的。这导致了所谓的机械异质性，其中电荷网络本质上是刚性的，而电荷耗尽区域是较软的、柔性的和移动的。这封信试图提供一个清晰和直观的摩擦之间的联系。与结构基序的动力学（特别是，电荷网络）。和山口最近的理论工作，联系随时间变化的粘度的离子液体的电荷交替峰的衰减的动态结构函数。我们提出，电荷模糊与正电荷和负电荷在网络内的记忆丧失是与离子液体粘度相关的关键机制。如果特征电荷模糊去相关时间低，则IL将具有低粘度。考虑到这一点，工程新的低粘度离子液体减少到了解如何最大限度地减少这一数量。
Prototypical ionic liquids (ILs) are characterized by three structural motifs associated with (1) vicinal interactions, (2) the formation of positive-negative charge-alternating chains or networks, and (3) the alternation of these networks with apolar domains. In recent articles, we highlighted that the friction and mobility in these systems are nowhere close to being spatially homogeneous. This results in what one could call mechanical heterogeneity, where charge networks are intrinsically stiff and charge-depleted regions are softer, flexible, and mobile. This Letter attempts to provide a clear and visual connection between friction.associated with the dynamics of the structural motifs (in particular, the charge network).and recent theoretical work by Yamaguchi linking the time-dependent viscosity of ILs to the decay of the charge alternation peak in the dynamic structure function. We propose that charge blurring associated with the loss of memory of where positive and negative charges are within networks is the key mechanism associated with viscosity in ILs. An IL will have low viscosity if a characteristic charge-blurring decorrelation time is low. With this in mind, engineering new low-viscosity ILs is reduced to understanding how to minimize this quantity.