A Self-Folding Polymer Film Based on Swelling Metal-Organic Frameworks

Javier Troyano,

[a] Arnau Carné-Sánchez,^[a] Javier Pérez-Carvajal,^[a] Laura León-Reina,^[b], Inhar Imaz,^[a] Aurelio Cabeza,^[c] Daniel Maspoch^*[a,d]

^[a] Dr. J. Troyano, Dr. A. Carné-Sánchez, Dr. J. Pérez-Carvajal, Dr. I. Imaz, Prof. D. Maspoch Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST Campus UAB, Bellaterra, 08193 Barcelona, Spain
E-mail: [email protected]
^[b] L. León-Reina Servicios Centrales de Apoyo a la Investigación, Universidad de Málaga, 29071 Málaga, Spain
^[c] Dr. A. Cabeza Dpto Química Inorgánica, Cristalografía y Mineralogía, Campus de Teatinos s/n, Universidad de Málaga, 29071 Málaga, Spain
^[d] Prof. D. Maspoch ICREA Pg. Lluís Companys 23, Barcelona, 08010, Spain

Abstract: Here, we exploit the well-known swelling behaviour of metal-organic frameworks (MOFs) to create a self-folding polymer film. Namely, we show that incorporating crystals of the flexible MOF MIL-88A into a polyvinylidene difluoride (PVDF) matrix affords a polymer composite film that undergoes reversible shape transformations upon exposure to polar solvents and vapours. Since the self-folding properties of this film correlate directly with the swelling properties of the MIL-88A crystals, it selectively bends to certain solvents and its degree of folding can be controlled by controlling the relative humidity. Moreover, it shows a shape-memory effect at relative humidity values from 60% to 90%. As proof-ofconcept, we demonstrate that these composite films can lift cargo and can be used to assemble 3D structures from 2D patterns. Our strategy is a straightforward method for designing autonomous soft materials whose folding properties can be tuned by judicious choice of the constituent flexible MOF.

Link to the article: https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201808433

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