Motevaselian Mohammad H, Aluru Narayana R
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
J Phys Chem Lett. 2020 Dec 17;11(24):10532-10537. doi: 10.1021/acs.jpclett.0c03219. Epub 2020 Dec 8.
Enhancement of parallel (- plane) dielectric permittivity of confined fluids has been shown previously. However, a theoretical model that explains this enhancement is lacking thus far. In this study, using statistical-mechanical theories and molecular dynamics simulations, we show an explicit relation between the parallel dielectric permittivity, density variations, and dipolar correlations for protic and aprotic fluids confined in slit-like channels. We analyze the importance of dipolar correlations on enhancement of parallel dielectric permittivity inside large channels and extreme confinements. In large channels, beyond the interfacial region, dipolar correlations exhibit bulk-like behavior. Under extreme confinement, the correlations become stronger to the extent that they give rise to a giant increase in the parallel dielectric permittivity. This sudden increase in dielectric permittivity can be a signature of a liquid transition into higher-ordered structures and has important consequences for understanding ion transport, molecular dissociation, and chemical reactions inside nanoconfined environments.
先前已表明受限流体的平行（平面）介电常数会增强。然而，迄今为止仍缺乏一个能解释这种增强现象的理论模型。在本研究中，我们运用统计力学理论和分子动力学模拟，揭示了限制在狭缝状通道中的质子性和非质子性流体的平行介电常数、密度变化及偶极相关性之间的明确关系。我们分析了偶极相关性对大通道内和平行介电常数增强及极端限制情况的重要性。在大通道中，超出界面区域，偶极相关性呈现类似本体的行为。在极端限制条件下，相关性变得更强，以至于导致平行介电常数大幅增加。介电常数的这种突然增加可能是液体转变为更高有序结构的一个标志，对于理解纳米受限环境中的离子传输、分子解离和化学反应具有重要意义。
