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Herein, we exploit the well-known swelling behaviour of metal–organic frameworks (MOFs) to create a selffolding 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 shapememory effect at relative humidity values from 60% to 90%. As proof of concept, 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 with folding properties that can be tuned by judicious choice of the constituent flexible MOF. Proyecto del MINECO MAT2013-41836-R y de la Junta de Andalucía P12-FQM-1656

Altres ajuts: Comunidad de Madrid project S2013/MIT-2740 (PHAMA_2.0). CERCA Programme/Generalitat de Catalunya Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data to show that truncated rhombic dodecahedral particles of the metal-organic framework (MOF) ZIF-8 can self-assemble into millimetre-sized superstructures with an underlying three-dimensional rhombohedral lattice that behave as photonic crystals. Those superstructures feature a photonic bandgap that can be tuned by controlling the size of the ZIF-8 particles and is also responsive to the adsorption of guest substances in the micropores of the ZIF-8 particles. In addition, superstructures with different lattices can also be assembled by tuning the truncation of ZIF-8 particles, or by using octahedral UiO-66 MOF particles instead. These well-ordered, sub-micrometre-sized superstructures might ultimately facilitate the design of three-dimensional photonic materials for applications in sensing.

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Geología y Geoquímica. Fecha de lectura: 12-02-2015

The development of devices for sensing and monitoring CO2 levels is crucial for many fields such as food packaging and for human safety indoors. Herein the fabrication of an optical CO2 sensor by integration of a metal–organic framework (MOF) onto bimodal optical waveguides is reported. This sensor is constructed via self-assembly of a transparent film of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles (size: 32 ± 5 nm) on the waveguides. The nanoZIF-8-based sensor exhibits a broad linear response, with limits of detection of 3130 ppm at room temperature and 774 ppm at 278 K. Furthermore, it is robust, selective, fast and reusable, and can be stored under humid conditions with no loss in performance., This work was supported by a grant from the Fundación Domingo Martínez (Ayuda a la Investigación 2016. Área de Aplicaciones Materiales), the Spanish MINECO (projects PN MAT2015-65354-C2-1-R and MAT2016-79053-P), the Catalan AGAUR (project 2014 SGR 80 and 2014 SGR 624), and the ERC, under the EU FP7 (ERC-Co 615954). It was also funded by the CERCA Program/Generalitat de Catalunya. This work also made use of the Spanish ICTS Network MICRONANOFABS, which is partially supported by MEINCOM. ICN2 and ICMAB acknowledge the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program, under Grants SEV-2013-0295 and SEV-2015-0496.