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Controlled Growth of Imine-Linked Two-Dimensional Covalent Organic Framework Nanoparticles

preprint
submitted on 18.01.2019 and posted on 21.01.2019 by Rebecca Li, Nathan C. Flanders, Austin Evans, Woojung Ji, Ioannina Castano, Lin Chen, Nathan Gianneschi, William Dichtel
Covalent organic frameworks (COFs) consist of monomers arranged in predictable structures with emergent properties. However, improved crystallinity, porosity, and solution processability remain major challenges. To this end, colloidal COF nanoparticles are useful for mechanistic studies of nucleation and growth and enable advanced spectroscopy and solution processing of thin films. Here we present a general approach to synthesize imine-linked 2D COF nanoparticles and control their size by favoring imine polymerization while preventing the nucleation of new particles. The method yields uniform, crystalline, and high-surface-area particles and is applicable to several imine-linked COFs. In situ X-ray scattering experiments reveal the nucleation of amorphous polymers, which crystallize via imine exchange processes during and after particle growth, consistent with previous mechanistic studies of imine-linked COF powders. The separation of particle formation and growth processes offers control of particle size and may enable further improvements in crystallinity in the future.

Funding

ARO W911NF-15-1-0447

DOE DE-AC0206CH11357

NSF DGE-1324585

NSF ECCS-1542205

NSF DMR-1720139

ARO W911NF-18-1-0359

History

Email Address of Submitting Author

wdichtel@northwestern.edu

Institution

Northwestern University

Country

United States

ORCID For Submitting Author

0000-0002-3635-6119

Declaration of Conflict of Interest

no conflict of interest

Version Notes

version 1.0

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