Viscosity and Wetting Property of Water Confined in Extended Nanospace Simultaneously Measured from Highly-Pressurized Meniscus Motion

Abstract

Understanding fluid and interfacial properties in extended nanospace (10-1000 nm) is important for recent advances of nanofluidics. We studied properties of water confined in fused-silica nanochannels of 50-1500 nm sizes with two types of cross-section: (1) square channel of nanoscale width and depth, and (2) plate channel of microscale width and nanoscale depth. Viscosity and wetting property were simultaneously measured from capillary filling controlled by megapascal external pressure. The viscosity increased in extended nanospace, while the wetting property was almost constant. Especially, water in the square nanochannels had much higher viscosity than the plate channel, which can be explained considering loosely coupled water molecules by hydrogen bond on the surface within 24 nm. This study suggests specificity of fluids two-dimensionally confined in extended nanoscale, in which the liquid is highly viscous by the specific water phase, while the wetting dynamics is governed by the well-known adsorbed water layer of several-molecules thickness.

Temperature and Size Effects on Structural and Dynamical Properties of Water Confined in 1 – 10 nm-scale Pores Using Proton NMR Spectroscopy

“…Such confined water was found to show unique properties differing from bulk water, e.g., higher viscosity, lower dielectric constant, enhancement of liquid conductivity, slower translational molecular motion, and higher protonic mobility compared with bulk water. [30][31][32][33][34][35] These results have suggested that local adsorbed water layers on surfaces and their electrostatic forces affect the collective behavior of bulklike hydration water in the nanochannel spaces.…”

Reversed-phase Chromatography in an Extended Nanospace: Separating Amino Acids in Short and Long Nanochannels

“…Here, E is the separation impedance and h is the reduced H. Based on the results of capillary filling experiments, 7 we estimated the separation impedance and permeability for a 2 mm length of nanochannel to be 580 and 5 -6 × 10 -14 m 2 , respectively. For a 10 mm channel, E and K became 13 and 47 × 10 -14 m 2 , respectively.…”

“…The solvent velocity and the viscosity in extended-nano channels can be estimated. 7 The total resolving power of a column corresponds to the total N, which is calculated as N = L/H. Generally, more efficient columns have a smaller H and a greater N.…”

Interfacial Phenomena and Fluid Control in Micro/Nanofluidics

“…7a). 47,50,118,119 By utilizing this structure, liquids are easily introduced into the nanofluidic channel by capillary filling. 47 The other technique is a pressure-driven method, where the pressure is controlled via the liquid pressure on the microfluidic channel section, which is connected to the nanofluidic channel (Fig.…”

“…By combining the capillary introduction and pressure-driven flow technique, the capillarity and liquid viscosity have been simultaneously measured. 119 Using a similar concept, Shui et al reported two-phase junctions in nanofluidic channels for small-droplet formation. 122 Recently, an improved version of the pressure-driven flow method, where solenoid valves are installed for pressure regulation and pressure control is realized with a 10-ms temporal resolution, was reported.…”