Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Chemistry, Imperial College of London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K.
J Phys Chem B. 2021 Mar 18;125(10):2677-2689. doi: 10.1021/acs.jpcb.0c09050. Epub 2021 Mar 9.
Here we present a theory of ion aggregation and gelation of room temperature ionic liquids (RTILs). Based on it, we investigate the effect of ion aggregation on correlated ion transport-ionic conductivity and transference numbers-obtaining closed-form expressions for these quantities. The theory depends on the maximum number of associations a cation and anion can form and the strength of their association. To validate the presented theory, we perform molecular dynamics simulations on several RTILs and a range of temperatures for one RTIL. The simulations indicate the formation of large clusters, even percolating through the system under certain circumstances, thus forming a gel, with the theory accurately describing the obtained cluster distributions in all cases. However, based on the strength and lifetime of associations in the simulated RTILs, we expect free ions to dominate ionic conductivity despite the presence of clusters, and we do not expect the percolating cluster to trigger structural arrest in the RTIL.
在这里，我们提出了一种室温离子液体（RTIL）的离子聚集和胶凝理论。基于该理论，我们研究了离子聚集对相关离子输运-离子电导率和迁移数的影响，得到了这些量的封闭形式表达式。该理论取决于阳离子和阴离子能够形成的最大缔合数以及它们的缔合强度。为了验证所提出的理论，我们对几种 RTIL 以及一种 RTIL 的一系列温度进行了分子动力学模拟。模拟表明，在某些情况下，即使在整个系统中也会形成大的簇，从而形成凝胶，在所有情况下，该理论都能准确描述所得到的簇分布。然而，根据模拟 RTIL 中缔合的强度和寿命，我们预计尽管存在簇，但自由离子仍将主导离子电导率，并且我们预计不会出现贯穿性簇引发 RTIL 结构停滞。
