Structure of water in mesoporous organosilica by calorimetry and inelastic neutron scattering

Esthy Levy, Alexander I. Kolesnikov, Jichen Li, Yitzhak Mastai

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13 Scopus citations

Abstract

In this paper, we describe the preparation of mesoporous organosilica samples with hydrophilic or hydrophobic organic functionality inside the silica channel. We synthesized mesoporous organosilica of identical pore sizes based on two different organic surface functionality namely hydrophobic (based on octyltriethoxysilane OTES) and hydrophilic (3-aminopropyltriethoxysilane ATES) and MCM-41 was used as a reference system. The structure of water/ice in those porous silica samples have been investigated over a range temperatures by differential scanning calorimetry (DSC) and inelastic neutron scattering (INS). INS study revealed that water confined in hydrophobic mesoporous organosilica shows vibrational behavior strongly different than bulk water. It consists of two states: water with strong and weak hydrogen bonds (with ratio 1:2.65, respectively), compared to ice-Ih. The corresponding O-O distances in these water states are 2.67 and 2.87 Ǻ, which strongly differ compared to ice-Ih (2.76 Ǻ). INS spectra for water in hydrophilic mesoporous organosilica ATES show behavior similar to bulk water, but with greater degree of disorder.

Original languageEnglish
Pages (from-to)71-77
Number of pages7
JournalSurface Science
Volume603
Issue number1
DOIs
StatePublished - Jan 1 2009
Externally publishedYes

Funding

Esthy Levy would like to acknowledge the Bar- Ilan President’s Ph.D. scholarship foundation. This research was supported by the Israel Science Foundation (ISF) Grant No. 289. The experiments at Argonne National Laboratory were supported by the Office of Basic Energy Sciences, Division of Materials Sciences, US Department of Energy, under Contract No. DE-AC02-06CH11357, and work at ORNL/SNS was managed UT-Battelle, LLC, for the US Department of Energy under Contract DE-AC05-00OR22725.

Keywords

  • Differential scanning calorimetry (DSC)
  • Ice
  • Inelastic neutron scattering
  • Mesoporous organosilica
  • Porous solids
  • Surface structure
  • Water

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