Capillary imbibition in pattern charged nanotubes

Capillary imbibition of water plays a significant role in various applications at both macroscopic and microscopic scales. However, it is still unclear how the capillary imbibition would be effected by the surface conditions, in particular, the charge patterns in the nanotubes. In this paper, we discuss the capillary imbibition dynamics in pattern charged nanotubes by molecular dynamics simulations. Two common charge patterns are considered, i.e. the adjacent charge pattern and barred charge pattern. It is found that velocity of the water imbibition in the barred pattern charged nanotube exhibits a strong impediment effect while the adjacent pattern charged nanotube shows no effect. By analyzing the microscopic distribution of the water molecules, it is found that the impediment effect originates from the decreased number of hydrogen bonds between the first monolayer water and the inner water shells, where a hexagonal ice-like hydrogen bond network of the water molecules would be induced in the first monolayer water by the barred charge pattern. The time variations of the filling length of the two charge patterns are also compared with the theoretical predictions in the continuous limit at the inertial and viscous regime respectively. Furthermore, it is also found that the impediment effect could be manipulated by varying the charge value and nanotube radius. Our results suggest a possible way to control the capillary imbibition behavior and it may have significant implications for water treatment, nanoswitches, catalysis engines and biological sensors.