The ice-like water monolayer near the wall makes inner water shells diffuse faster inside a charged nanotube

J Chem Phys. 2013 May 28;138(20):204710. doi: 10.1063/1.4807383.

Abstract

Using molecular dynamics simulations, we have investigated the impact of the ice-like water monolayer inside the tube and nearest to the tube wall on the diffusion properties of other inner water shells confined within a charged nanotube. We find that the axial diffusion coefficient of the first water monolayer near the wall monotonously decreases with the charge size on the nanotube, indicating a tighter control of the first monolayer from the larger sized charge. However, for the other water shells, the diffusion coefficients increase when the charge is larger than a critical value qc (~1.0 e). This unexpected phenomenon is attributed to the decreased number of hydrogen bonds between the first monolayer and other inner water shells caused by the very unique hydrogen-bond network patterns in the first ice-like monolayer, which makes it behave like a "hydrophobic water layer." Our findings may have implications for water treatment, non-fouling surfaces, catalysis engine, and biological sensor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diffusion
  • Hydrogen Bonding
  • Molecular Dynamics Simulation*
  • Nanotubes / chemistry*
  • Water / chemistry*

Substances

  • Water