Capillary rise of water in hydrophilic nanopores.
We report on the capillary rise of water in three-dimensional networks of hydrophilic silica pores with 3.5 nm and 5 nm mean radii, respectively (porous Vycor monoliths). We find classical square root of time Lucas-Washburn laws for the imbibition dynamics over the entire capillary rise times of up to 16 h investigated. Provided we assume two preadsorbed strongly bound layers of water molecules resting at the silica walls, which corresponds to a negative velocity slip length of -0.5 nm for water flow in silica nanopores, we can describe the filling process by a retained fluidity and capillarity of water in the pore center. This anticipated partitioning in two dynamic components reflects the structural-thermodynamic partitioning in strongly silica bound water layers and capillary condensed water in the pore center which is documented by sorption isotherm measurements.
Gruener
Simon
S
Faculty of Physics and Mechatronics Engineering, Saarland University, D-66041 Saarbrücken, Germany. s.gruener@mx.uni-saarland.de
Hofmann
Tommy
T
Wallacher
Dirk
D
Kityk
Andriy V
AV
Huber
Patrick
P