Electric fields can control the transport of water in carbon nanotubes

Abstract

The properties of water confined inside nanotubes are of considerable scientific and technological interest. We use molecular dynamics to investigate the structure and average orientation of water flowing within a carbon nanotube. We find that water exhibits biaxial paranematic liquid crystal ordering both within the nanotube and close to its ends. This preferred molecular ordering is enhanced when an axial electric field is applied, affecting the water flow rate through the nanotube. A spatially patterned electric field can minimize nanotube entrance effects and significantly increase the flow rate.

Diffusion behaviour of water confined in deformed carbon nanotubes

“…[16]. For the two models, the diffusion coefficient shows a global minimum at 1 nm diameter which corresponds to a (9,9) CNT. In this case the mobility of molecules is virtually zero.…”

“…For instance, the water diffusion coefficient in pristine carbon nanotubes does not decreases monotonically with the diameter of the tube [16]. Instead, it has a minimum for the (9,9) CNT, a maximum for the (20,20) nanotube and it approaches the bulk value for larger tubes. The nanoconfined water forms layers and molecules near the wall diffuse faster than the particles in the middle of the tube.…”

“…In the case of water this shows an even larger impact. When confined in carbon nanotubes (CNTs) water exhibits flow rates which exceeds by three orders of magnitude the values predicted by the continuum hydrodynamic theory [3][4][5][6][7][8][9][10][11][12]. The superflow is not the only anomalous behavior observed in nanoconfined water.…”

Nanofluidic Behaviors of Water and Ions in Covalent Triazine Framework (CTF) Multilayers

“…The possible reason is the lower friction for water molecules passing through CTF‐2 pores due to the hydrophobic pore wall of CTF‐2, where there are few strong polar atoms or groups. However, such hydrophobic nature increases the R interfacial due to the worse wettability …”

Uncertainty Quantification at the Molecular–Continuum Model Interface

“…A major challenge in hybrid modelling is the quality of the information exchanged between domains, as well as the efficiency of the inter-scale communication. Molecular dynamics (MD) is a powerful tool for capturing phenomena at the atomic level [2][3][4][5], but the method relies on the accuracy of the potential (or force-field) with which the inter-atomic forces of a real system can be reproduced [6]. A widely used model of molecular interactions is the Lennard-Jones (LJ) potential, defined for particles located at r i and r j as [7]: …”