Effects of Phase Purity and Pore Reinforcement on Mechanical Behavior of NU-1000 and Silica-Infiltrated NU-1000 Metal-Organic Frameworks

Zhao Wang, Kevin M. Schmalbach, Rebecca L. Combs, Youxing Chen, R. Lee Penn, Nathan A. Mara, Andreas Stein

Research output: Contribution to journalArticlepeer-review

Abstract

Metal-organic framework (MOF) materials have shown promise in many applications, ranging from gas storage to absorption and catalysis. Because of the high porosity and low density of many MOFs, densification methods such as pelletization and extrusion are needed for practical use and for commercialization of MOF materials. Therefore, it is important to elucidate the mechanical properties of MOFs and to develop methods of further enhancing their mechanical strength. Here, we demonstrate the influence of phase purity and the presence of a pore-reinforcing component on elastic modulus and yield stress of NU-1000 MOFs through nanoindentation methods and finite element simulation. Three types of NU-1000 single crystals were compared: phase-pure NU-1000 prepared with biphenyl-4-carboxylic acid as a modulator (NU-1000-bip), NU-1000 prepared with benzoic acid as a modulator (NU-1000-ben), which results in an additional, denser impurity phase of NU-901, and NU-1000-bip whose mesopores were infiltrated with silica (SiOx(OH)y@NU-1000) by nanocasting methods. By maintaining phase purity and minimizing defects, the elastic modulus could be enhanced by nearly an order of magnitude: phase-pure NU-1000-bip crystals exhibited an elastic modulus of 21 GPa, whereas the value for NU-1000-ben crystals was only 3 GPa. The introduction of silica into the mesopores of NU-1000-bip did not strongly affect the measured elastic modulus (19 GPa) but significantly increased the load at failure from 2000 μN to 3000-4000 μN.

Original languageEnglish (US)
JournalACS applied materials & interfaces
DOIs
StatePublished - Nov 4 2020

Bibliographical note

Funding Information:
Mechanical testing and sample characterization described in this work were primarily supported by the MRSEC Program of the National Science Foundation under Award Number DMR-2011401. Synthesis of the materials was supported as part of the Inorganometallic Catalysis Design Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award DE-SC0012702. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing resources that contributed to the research results reported within this paper. The authors thank Antonia Antoniou at the Georgia Institute of Technology for helpful discussions regarding finite element modeling, the Hupp and Farha groups from Northwestern University for providing HTBAPy linkers for the MOF synthesis, Dr. L. Chip Reisman for carrying out TGA measurements, and Yuan Sheng for carrying out H NMR measurements. 4 1

Keywords

  • finite element simulation
  • metal-organic frameworks
  • nanocasting
  • nanoindentation
  • NU-1000
  • silica-reinforced NU-1000

How much support was provided by MRSEC?

  • Partial

Reporting period for MRSEC

  • Period 7
  • Period 1

PubMed: MeSH publication types

  • Journal Article

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