Tiny windows in reticular nanomaterials for molecular sieving gas separation membranes

Abstract

The current state of reticular chemistry enables the synthesis of a wide range of highly porous nanomaterials for gas separation, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), porous organic cages (POCs), metal-organic cages (MOCs), and polyhedra (MOPs). This perspective focuses on membrane technology, a key player in energy-efficient gas separations. It explores the world of reticular materials, taking a glance at tiny pore windows with narrow openings, which are ideal for high-resolution molecular sieving, and how to design them. Promising concepts in this field are membranes consisting of neat materials, but also mixed matrix membranes, where polymeric films incorporate reticular fillers, creating cost-efficient membranes. This article sheds light on the potential use of reticular materials as membrane components. The reticular synthesis of MOFs offers the ability to separate gas molecules with minimal size differences effectively. For COFs, the crucial factor lies in reducing their pore size, preferably through functional group modifications. Porous cage compounds can achieve fine distribution from homogeneous dispersions into polymers making them excellent candidates for mixed matrix membranes. This perspective provides strategies and guiding principles for the future of reticular nanomaterials-based membranes, addressing the pressing need for advanced and efficient separation technologies.