Viscoelectric Effects in Nanochannel Electrokinetics
Viscoelectric Effects in Nanochannel Electrokinetics
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DOI：
10.1021/acs.jpcc.7b06798
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发表时间：
2017-09-21
影响因子：
3.7
通讯作者：
Daiguji, Hirofumi
中科院分区：
文献类型：
--
作者：
Hsu, Wei-Lun;Harvie, Dalton J. E.;Daiguji, Hirofumi
纳米通道中的电动输运行为与大尺寸通道中的不同。纳米通道中的分子动力学（MD）模拟已经证明了两种在微通道中未观察到的知之甚少的现象，即随着表面电荷的增加，（i）在高表面电荷密度下的平均电渗迁移率和（ii）在高盐浓度下的通道电导的降低。然而，目前的双电层（EDL）模型没有捕捉到这些结果。在这里，我们提供的证据表明，这种不一致主要是由于忽略了传统的电动连续模型中的粘电（VE）效应。我们提出了一个修改后的连续模型，其中包括VE固定层和粘电层（VEL）的概念，并再现上述纳米通道的具体现象。结果表明，基于先前MD结果估计的理论VE系数（2.3 × 10 ~（-16）m ~（2）/V ~（-2））接近于先前的实验估计值（5-10 × 10 ~（-16）m ~（2）/V ~（-2））。
Electrokinetic transport behavior in nanochannels is different to that in larger-sized channels. Molecular dynamics (MD) simulations in nanochannels have demonstrated two poorly understood phenomena which are not observed in microchannels, being the decreases of (i) average electroosmotic mobility at high surface charge density and (ii) channel conductance at high salt concentrations, as the surface charge is increased. However, current electric double layer (EDL) models do not capture these results. Here we provide evidence that this inconsistency primarily arises from the neglect of viscoelectric (VE) effects in conventional electrokinetic continuum models. We propose a modified continuum model that includes the concepts of a VE immobile layer and a viscoelectric layer (VEL) and that reproduces the above-mentioned nanochannel-specific phenomena. It is shown that the theoretical VE coefficient, estimated based on previous MD results (2.3 X 10(-16) m(2)/V-2), is close to previous experimental estimates (5-10 x 10(-16) m(2)/V-2).