Role of Confinement and Surface Affinity on Filling Mechanisms and Sorption Hysteresis of Water in Nanopores

EZEQUIEL DE LA LLAVE; VALERIA MOLINERO; D. A. SCHERLIS

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 116 p. 1833 - 1840

1932-7447

The liquidvapor transition in cylindrical pores isstudied as a function of pore size and hydrophilicity throughmolecular dynamics simulations with the mW coarse-grainedmodel of water. We identify two distinct filling mechanisms,depending on whether the waterpore interaction is smaller orlarger than the waterwater interaction. In the former case (that weterm hydrophobic pore), the formation of the condensed phaseproceeds gradually with filling, through the nucleation of a watercluster which grows toward the center of the cavity. In hydrophilicpores, instead, the condensed phase develops in conditions ofsupersaturation, which in principle become more extreme with increasing pore radius and surface affinity. For highly hydrophilicinterfaces (those with adsorption energy for water above 10 kcal/mol), the equilibrium and dynamical properties of water inconfinement turn out to be practically independent of water affinity.