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Seeded Growth of Single-Crystal Two-Dimensional Covalent Organic Frameworks

submitted on 14.12.2017, 14:44 and posted on 14.12.2017, 16:25 by Austin M. Evans, Lucas R. Parent, Nathan C. Flanders, Ryan P. Bisbey, Edon Vitaku, Lin X. Chen, Nathan C. Gianneschi, William Dichtel

Polymerizing monomers into periodic two-dimensional (2D) networks provides structurally precise, atomically thin macromolecular sheets linked by robust, covalent bonds. These materials exhibit desirable mechanical, optoelectrotronic, and molecular transport properties derived from their designed structure and permanent porosity. 2D covalent organic frameworks (COFs) offer broad monomer scope, but are generally isolated as polycrystalline, insoluble powders with limited processability. Here we overcome this limitation by controlling 2D COF formation using a two- step procedure. In the first step, 2D COF nanoparticle seeds are prepared with approximate diameters of 30 nm. Next, monomers are slowly added to suppress new nucleation while promoting epitaxial growth on the existing seeds to sizes of several microns. The resulting COF nanoparticles are of exceptional and unprecedented quality, isolated as single crystalline materials with micron-scale domain sizes. These findings advance the controlled synthesis of 2D layered COFs and will enable a broad exploration of synthetic 2D polymer structures and properties.


ARO W911NF-15-1-0447 (WRD), NSF DGE-1324585 (AME), NSF NNCI-1542205, NSF ECCS1542205, NIH F32EB021859 (LRP), ARO W911NF-5-1-0568 (NCG), NSF 0960140 (LXC)



  • Organic Polymers
  • Polymerization (Polymers)
  • Polymerization kinetics

Email Address of Submitting Author

Email Address(es) for Other Author(s)

Austin Evans Lucas Robert Parent Nathan Flanders Ryan Patrick Bisbey Edon Vitaku Lin X Chen Nathan Gianneschi


Northwestern University



ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest