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By Dr Gaëlle Le Fer, University of Lille, CNRS, INRAE, Lille, France

Abstract: 

Covalent organic frameworks (COFs) are crystalline porous materials whose topology and pore size can be precisely programmed through the molecular design of their building blocks.^1,2 A central challenge is to extend this molecular programmability to larger length scales, where crystal orientation, particle architecture and collective organization determine how the intrinsic properties of COFs can be translated into functional materials.³

Our approach combines reticular chemistry and macromolecular chemistry, using linear polymers as active vectors of supramolecular organization. Rather than simply acting as additives, the polymers interact with COF building blocks, modulating nucleation, crystal growth, and the assembly of crystalline domains. Through these interactions, they can shape COF organization across multiple length scales, from local molecular organization to crystal orientation and particle morphology. This approach has enabled us to access different COF particle architectures, including raspberry-like particles with radial crystal orientation⁴ and hollow spheres with porous membranes.⁵ These hollow architectures provide a direct link between structure and function: their porous membranes can regulate molecular transport, allowing the particles to operate as size-selective microreactors. We also highlighted the potential of these hollow COF particles to reorganize within polymer gels into elongated micrometer-scale tubular structures, revealing a new level of hierarchical organization.

Overall, these results show how polymers can guide COF organization from crystal growth to particle assembly. More broadly, they show that COFs are not only static porous solids, but can also behave as dynamic systems capable of evolving and reorganizing in response to their environment. This dynamic behavior opens new opportunities for COF-based materials with adaptive properties.

References:

1. Cote, A. P., Benin, A. I.;,Ockwig, N. W., O'Keeffe, M., Matzger, A. J.,Yaghi, O. M. Porous, crystalline, covalent organic frameworks. Science 2005, 310 (5751), 1166.
2. Bisbey, R. P., Dichtel, W. R. Covalent organic frameworks as a platform for multidimensional polymerization. ACS central science 2017, 3 (6), 533.
3. Dey, K.; Mohata, S.; Banerjee, R. Covalent organic frameworks and supramolecular nano-synthesis. ACS Nano 2021, 15 (8), 12723.
4. Salaün, P., Fadel A., Pelaez‐Fernandez, M., Mouloud, B.‐, Tahon, J.-F., Volkringer, C., Addad, A., Woisel, P., Le Fer, G. Cooperative synthesis of raspberry‐like covalent organic framework‐polymer particles with a radial single‐crystal grain orientation, Small 2023, 19 (49), 2303697.
5. Salaün, P., Mouloud, B.-E., Richard, E. ,Mariani, V. Tahon, J.-F., Addad, A., Grazon, C., Woisel, P., Le Fer, G. Polymer-driven self-templated synthesis of boronate-COF hollow spheres: toward the development of nanoreactors, ACS Applied Materials and Interfaces 2026, DOI:1021/acsami.6c06835.

Short bio:

Gaëlle Le Fer is a CNRS researcher since 2020, in the “Unité Matériaux et Transformations” (UMR 8207) in Lille, France. In 2015, she obtained a PhD in chemistry (Université Paris-Est) at the Institut de Chimie et des Matériaux Paris-Est (UMR 7182). Her PhD thesis was focused on the development of polymer nanoparticles. Following her interest in polymer self-assembly, she joined the group of Prof. Sébastien Lecommandoux at the Laboratoire de Chimie des Polymères Organiques (UMR 5629) for a 2-year post-doctorate. Then, she moved to the Prof. Matthew Becker’s group at the University of Akron, USA, for a second 2-year postdoc. She designed and characterized 3D-printed porous shape-memory materials. Currently, she is developing her own topic on materials combining both COFs and polymers. She supervised three PhD students and four postdocs, was the coordinator of one ANR, one international chair with Ghent University (Belgium) and one CNRS-Emergence project.

Hosted by ICREA Prof. Daniel Maspoch, Group Leader, Supramolecular Nanochemistry ans Materials group at ICN2.