Influence of the pore length on the properties of water confined in a silica nanopore

Abstract

Molecular dynamics simulations were carried out to investigate the effect of the pore length on the structural, dielectric and dynamic properties of water confined in a silica cylindrical nanopore of 6 Å in radius where the planar silica/water interfaces were taken into account explicitly. Four different pore lengths and two sizes of reservoirs were studied. Structural properties (water layering and hydrogen bond density) and diffusivity of confined water are not impacted by the pore length. On the other hand, dielectric properties are strongly influenced by the pore length. The radial component of the dielectric tensor decreases as a longer pore is considered, whereas the opposite trend is observed for the axial component. This dielectric behaviour is correlated to the fluctuations of the hydrogen bond network. A more cohesive structure was observed in the confined direction for the longest pore size.

Keywords:

• molecular dynamics
• nanopore
• confinement
• water
• silica

Additional information

Funding

The authors are grateful to the Agence Nationale de la Recherche for its financial support through the program MUTINA [grant number ANR 2011 BS09 002].