In Situ Small-Angle Neutron Scattering Investigation of Adsorption-Induced Deformation in Silica with Hierarchical Porosity

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Authors

  • Christian Balzer
  • Anna M. Waag
  • Stephan Braxmeier
  • Florian Putz
  • Sebastian Busch
  • Gennady Y. Gor
  • Alexander V. Neimark
  • Nicola Hüsing
  • Gudrun Reichenauer

External Organisational units

  • Bavarian Center for Applied Energy Research, Wuerzburg, Germany
  • SMBS - University of Salzburg Business School, Sigmund-Haffner-Gasse 18, A-5020 Salzburg, Austria
  • Institute of Coastal Research
  • University of New Jersey
  • Otto H. York Department of Chemical, Biological, and Pharmaceutical Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102

Abstract

Adsorption-induced deformation of a series of silica samples with hierarchical porosity has been studied by in situ small-angle neutron scattering (SANS) and in situ dilatometry. Monolithic samples consisted of a disordered macroporous network of struts formed by a 2D lattice of hexagonally ordered cylindrical mesopores and disordered micropores within the mesopore walls. Strain isotherms were obtained at the mesopore level by analyzing the shift of the Bragg reflections from the ordered mesopore lattice in SANS data. Thus, SANS essentially measured the radial strain of the cylindrical mesopores including the volume changes of the mesopore walls due to micropore deformation. A H2O/D2O adsorbate with net zero coherent neutron scattering length density was employed in order to avoid apparent strain effects due to intensity changes during pore filling. In contrast to SANS, the strain isotherms obtained from in situ dilatometry result from a combination of axial and radial mesopore deformation together with micropore deformation. Strain data were quantitatively analyzed with a theoretical model for micro-/mesopore deformation by combining information from nitrogen and water adsorption isotherms to estimate the water-silica interaction. It was shown that in situ SANS provides complementary information to dilatometry and allows for a quantitative estimate of the elastic properties of the mesopore walls from water adsorption.

Details

Original languageEnglish
Pages (from-to)11590-11600
Number of pages11
JournalLangmuir
Volume35.2019
Issue number35
Early online date4 Aug 2019
DOIs
Publication statusPublished - 3 Sept 2019