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Title: Water confinement in nanoporous silica materials

The influence of the surface polarity of cylindrical silica nanopores and the presence of Na{sup +} ions as compensating charges on the structure and dynamics of confined water has been investigated by molecular dynamics simulations. A comparison between three different matrixes has been included: a protonated nanopore (PP, with SiOH groups), a deprotonated material (DP, with negatively charged surface groups), and a compensated-charge framework (CC, with sodium cations compensating the negative surface charge). The structure of water inside the different pores shows significant differences in terms of layer organization and hydrogen bonding network. Inside the CC pore the innermost layer is lost to be replaced by a quasi bulk phase. The electrostatic field generated by the DP pore is felt from the surface to the centre of pore leading to a strong orientation of water molecules even in the central part of the pore. Water dynamics inside both the PP and DP pores shows significant differences with respect to the CC pore in which the sub-diffusive regime of water is lost for a superdiffusive regime.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. Institut des Sciences Chimiques de Rennes – UMR CNRS 6226, Université de Rennes 1, 263 Ave. General Leclerc, 35042 Rennes (France)
  2. (France)
  3. Institut de Physique de Rennes–Université de Rennes - UMR CNRS 6251, Université de Rennes 1, 263 Ave. General Leclerc, 35042 Rennes (France)
Publication Date:
OSTI Identifier:
22255227
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CATIONS; MOLECULAR DYNAMICS METHOD; SILICA; SIMULATION; SODIUM IONS; SURFACES; WATER