Renou R, Szymczyk A, Ghoufi A
Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042 Rennes, France and Université Européenne de Bretagne, France.
Institut de Physique de Rennes, UMR 6251 CNRS, Université de Rennes 1, 263 avenue Général Leclerc, 35042 Rennes, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Mar;91(3):032411. doi: 10.1103/PhysRevE.91.032411. Epub 2015 Mar 20.
Using molecular dynamics simulations, the influence of the surface charge density of a nanotube on the static dielectric permittivity ε of confined water was reported. Whereas the dielectric anisotropy between the radial and axial directions of water confined in hydrophilic and hydrophobic membranes and the increase in axial dielectric permittivity with respect to the bulk value have previously been described, we found that an increase in the surface charge density leads to a drastic decrease in ε into the axial direction. The decrease in ε is accompanied by a strong slowdown in the rotational dynamics of water molecules. We show that this effect is due to the strong orientation of water molecules induced by the surface charge. Thus, by controlling the surface charge in nanotubes and nanocavities, it is possible to tune the dielectric permittivity of confined fluids at the nanoscale.
通过分子动力学模拟，报道了纳米管表面电荷密度对受限水的静态介电常数ε的影响。虽然先前已经描述了限制在亲水和疏水膜中的水在径向和轴向之间的介电各向异性以及轴向介电常数相对于本体值的增加，但我们发现表面电荷密度的增加会导致轴向方向上的ε急剧下降。ε的下降伴随着水分子旋转动力学的强烈减慢。我们表明，这种效应是由于表面电荷诱导的水分子的强烈取向。因此，通过控制纳米管和纳米腔中的表面电荷，可以在纳米尺度上调节受限流体的介电常数。
