title: Water confinement in nanoporous silica materials.
abstract: The influence of the surface polarity of cylindrical silica nanopores and the presence of Na(+) 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: Institut des Sciences Chimiques de Rennes - UMR CNRS 6226, Université de Rennes 1, 263 Ave. General Leclerc, 35042 Rennes, France.
authors: Richard
authors: R
authors: Renou
authors: Institut des Sciences Chimiques de Rennes - UMR CNRS 6226, Université de Rennes 1, 263 Ave. General Leclerc, 35042 Rennes, France.
authors: Anthony
authors: A
authors: Szymczyk
authors: Institut de Physique de Rennes-Université de Rennes - UMR CNRS 6251, Université de Rennes 1, 263 Ave. General Leclerc, 35042 Rennes, France.
authors: Aziz
authors: A
authors: Ghoufi
mesh_terms: D002412:Cations / Q000737:chemistry; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D058608:Nanopores; D012822:Silicon Dioxide / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D002412:Cations; D014867:Water; D012822:Silicon Dioxide; D012964:Sodium