Mechanical Characterization of Hierarchical Structured Porous Silica by in Situ Dilatometry Measurements during Gas Adsorption

Christian Balzer, Anna M. Waag, Florian Putz, Nicola Huesing, Oskar Paris, Gennady Y. Gor, Alexander, V Neimark, Gudrun Reichenauer

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung

9 Zitate (Scopus)

Abstract

Mechanical properties of hierarchically structured nanoporous materials are determined by the solid phase stiffness and the pore network morphology. We analyze the mechanical stiffness of hierarchically structured silica monoliths synthesized via a sol-gel process, which possess a macroporous scaffold built of interconnected struts with hexagonally ordered cylindrical mesopores. We consider samples with and without microporosity within the mesopore walls and analyze them on the macroscopic level as well as on the microscopic level of the mesopores. Untreated as-prepared samples still containing some organic components and the respective calcined and sintered counterparts of varying microporosity are investigated. To determine Young's moduli on the level of the macroscopic monoliths, we apply ultrasonic run time measurements, while Young's moduli of the mesopore walls are obtained by analysis of the in situ strain isotherms during N 2 adsorption at 77 K. For the latter, we extended our previously reported theoretical approach for this type of materials by incorporating the micropore effects, which are clearly not negligible in the calcined and most of the sintered samples. The comparison of the macro- and microscopic Young's moduli reveals that both properties follow essentially the same trends, that is, calcination and sintering increase the mechanical stiffness on both levels. Consequently, stiffening of the monolithic samples can be primarily attributed to stiffening of the backbone material which is consistent with the fact that the morphology on the mesopore level is mainly preserved with the post-treatments applied.
OriginalspracheEnglisch
Seiten (von - bis)2948-2956
Seitenumfang9
FachzeitschriftLangmuir
Jahrgang35.2019
Ausgabenummer8
DOIs
PublikationsstatusVeröffentlicht - 26 Feb. 2019

Bibliographische Notiz

Funding Information:
We acknowledge financial support from the German Science Foundation DFG (project GZ: RE1148/10-1) and the Austrian Science Foundation FWF (project I 1605-N20) in the framework of the DACH agreement and the National Science Foundation (award no. 1834345 to A.V.N.).

Publisher Copyright:
© 2019 American Chemical Society.

Dieses zitieren