Gravelle Simon, Joly Laurent, Ybert Christophe, Bocquet Lydéric
Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne cedex, France.
J Chem Phys. 2014 Nov 14;141(18):18C526. doi: 10.1063/1.4897253.
In fluid transport across nanopores, there is a fundamental dissipation that arises from the connection between the pore and the macroscopic reservoirs. This entrance effect can hinder the whole transport in certain situations, for short pores and/or highly slipping channels. In this paper, we explore the hydrodynamic permeability of hourglass shape nanopores using molecular dynamics (MD) simulations, with the central pore size ranging from several nanometers down to a few Angströms. Surprisingly, we find a very good agreement between MD results and continuum hydrodynamic predictions, even for the smallest systems undergoing single file transport of water. An optimum of permeability is found for an opening angle around 5°, in agreement with continuum predictions, yielding a permeability five times larger than for a straight nanotube. Moreover, we find that the permeability of hourglass shape nanopores is even larger than single nanopores pierced in a molecular thin graphene sheet. This suggests that designing the geometry of nanopores may help considerably increasing the macroscopic permeability of membranes.
在通过纳米孔的流体传输中，由于孔与宏观储液器之间的连接会产生一种基本的耗散。这种入口效应在某些情况下，比如短孔和/或高度滑移通道中，会阻碍整体传输。在本文中，我们使用分子动力学（MD）模拟来探究沙漏形纳米孔的流体动力学渗透率，其中心孔径范围从几纳米到几埃。令人惊讶的是，即使对于经历水的单列传输的最小系统，我们也发现MD结果与连续介质流体动力学预测之间有非常好的一致性。与连续介质预测一致，在开口角度约为5°时发现了渗透率的最佳值，其渗透率比直纳米管大五倍。此外，我们发现沙漏形纳米孔的渗透率甚至比分子薄石墨烯片中单个纳米孔的渗透率还要大。这表明设计纳米孔的几何形状可能有助于显著提高膜的宏观渗透率。
