Metal–organic framework nanosheets in polymer composite materials for gas separation

• Published in: Nature materials 2015-01, Vol.14 (1), p.48-55
• Main Authors: Rodenas, Tania, Luz, Ignacio, Prieto, Gonzalo, Seoane, Beatriz, Miro, Hozanna, Corma, Avelino, Kapteijn, Freek, Llabrés i Xamena, Francesc X., Gascon, Jorge
• Format: Article
• Language: English
• Subjects: 121/135; 639/301/299/921; Biomaterials; Carbon dioxide; Composite materials; Condensed Matter Physics; Crystals; Doors; Gas separation; letter; Materials Science; Metal-organic frameworks; Methane; Nanostructure; Nanostructured materials; Nanotechnology; Occupation; Optical and Electronic Materials; Permeation; Polymer blends; Polymer matrix composites; Polymers; Separation; Stems
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat4113

A bottom-up approach for producing metal–organic framework lamellae of micrometre lateral dimensions and nanometre thickness that can be incorporated into polymer matrices is now presented. These composite materials exhibit outstanding CO 2 separation performances on exposure to CO 2 /CH 4 gas mixtures. Composites incorporating two-dimensional nanostructures within polymeric matrices have potential as functional components for several technologies, including gas separation. Prospectively, employing metal–organic frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of freestanding nanosheets has proved challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometre lateral dimensions and nanometre thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO 2 separation performance from CO 2 /CH 4 gas mixtures, together with an unusual and highly desired increase in the separation selectivity with pressure. As revealed by tomographic focused ion beam scanning electron microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared with isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF–polymer composites for various applications.