Kinetics of water filling the hydrophobic channels of narrow carbon nanotubes studied by molecular dynamics simulations

Abstract

The kinetics of water filling narrow single-walled carbon nanotubes was studied using molecular dynamics simulations. The time required to fully fill a nanotube was linear with respect to the tube length. We observed that water molecules could enter into nanotubes of different lengths, either from one end or from both ends. The probability of having a nanotube filled completely from both ends increased exponentially with the tube length. For short tubes, filling usually proceeded from only one end. For long tubes, filling generally proceeded from both tube ends over three stages, i.e., filling from one end, filling from both ends, and filling from both ends with the dipole reorientation of water molecules to give a concerted ordering within the fully filled tube. The water molecules in the partially filled nanotube were hydrogen bonded similarly to those in the fully filled nanotube. Simulations for the reference Lennard-Jones fluid without hydrogen bonds were also performed and showed that the filling behavior of water molecules can be attributed to strong intermolecular hydrogen bonding.

Simulations of water transport through carbon nanotubes: How different water models influence the conduction rate

“…For example, channel size, 18,27 charge modification, 22 chemical modification, 19 and nanotube defects 25 have been considered. However, we note that in most simulation studies a particular water model, such as TIP3P, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]30 SPC/E, [7][8][9]31 TIP5P, [26][27][28]32 etc., has been adopted, but there has been little discussion of how different water models might influence flow rates. Some authors have considered more than one water model, and have noted some similarities and differences, 29 but there appears to have been no systematic study of different models under pressure-driven, non-equilibrium conditions.…”

Capillary filling with giant liquid/solid slip: Dynamics of water uptake by carbon nanotubes

“…In recent years, many works have investigated capillary filling at the nanoscale, emphasizing the roles of dynamic contact angle, liquid inertia, and liquid-solid slip [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] . In this context, recent experiments [27][28][29][30] and numerical simulations 31,32 have reported slip lengths of water (and other liquids) in carbon nanotubes (CNT) much larger than the tube radius.…”

Competition between hydrogen bonding and electric field in single-file transport of water in carbon nanotubes

“…Despite its strong hydrophobic character, single walled carbon nanotubes (SWCNTs) are spontaneously filled by water [1,2]. Transport of water in these systems has novel and promising properties which have been extensively studied by Molecular Dynamics (MD) simulations (see for example [3] for a review).…”

“…In the case of the nanotubes with small radius, the nanotubes are filled by a one-dimensional ordered chain of water molecules which maintain 2 hydrogen bonds per molecule inside the CNT [6]. This effective 1D water system has extremely interesting properties and it has been studied experimentally [5], by MD simulations [1][2][3][4][6][7][8] and analytical treatments based on the 1D Ising model [9]. Interestingly, this system has been analyzed as a model for water transport in biological pores [10].…”