Self-supporting covalent organic framework membranes synthesized through two different processes: solvothermal annealing and solvent vapor annealing

Nikka Turangan; Yanan Xu; Henry Spratt; Llewellyn Rintoul; Steven Bottle; Jennifer MacLeod

doi:10.1088/1361-6528/abb903

Self-supporting covalent organic framework membranes synthesized through two different processes: solvothermal annealing and solvent vapor annealing

Nanotechnology. 2021 Feb 12;32(7):075604. doi: 10.1088/1361-6528/abb903.

Authors

Nikka Turangan^{1

2}, Yanan Xu³, Henry Spratt³, Llewellyn Rintoul³, Steven Bottle^{1

2}, Jennifer MacLeod^{1

2}

Affiliations

¹ School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane 4000, Australia.
² Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane 4000, Australia.
³ Institute of Future Environments (IFE), Queensland University of Technology (QUT), 2 George Street, Brisbane 4000, Australia.

PMID: 32937612
DOI: 10.1088/1361-6528/abb903

Abstract

Rigid, freestanding covalent organic framework (COF-1) membranes have been synthesized from 1,4-benzenediboronic acid (BDBA) precursors using two different approaches: room temperature solvent-vapour annealing (SVA) and solvothermal annealing (SA). Characterization of films using Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and various microscopies shows that the films obtained through the two different routes vary in their retained BDBA proportion, crystal size and macroscale morphology. Gas adsorption measurements give specific surface areas of 579 ± 7 m² g^-1 and 739 ± 11 m² g^-1 respectively, suggesting that the average porosity of these films is competitive with bulk-synthesized COF-1 particles. The films have a stratified structure, with a dense, thin top layer and a thicker, sponge-like base layer. Using nanoindentation, we measured the Young's modulus at the top surface of the SVA and SA films to be 3.64 ± 1.20 GPa and 3.33 ± 0.12 GPa respectively, with the smaller uncertainty for the SA film attributed to a more uniform morphology. These measurements provide useful experimental data pertaining to COF-1 mechanical properties, furnishing information relevant to the use of these free-standing membranes in applications such as gas filtration or storage.