Researchers solve long-standing puzzle of porous soft materials

Researchers from Japan have made a groundbreaking discovery regarding porous soft materials, specifically metal-organic frameworks (MOFs). These materials have been studied extensively for their unique properties and applications. The research, recently published in Proceedings of the National Academy of Sciences by the Institute of Industrial Science, The University of Tokyo, sheds light on the crucial role of elastic heterogeneity in tuning the adsorption and desorption properties of MOFs.

MOFs are sponge-like materials with high tunability, allowing their properties to be adjusted by changing the metal ions and organic linkers used in their construction. This tunability affects their mechanical flexibility and responsiveness to different stimuli when they adsorb guest molecules. Understanding the relationship between macroscopic elasticity and microscopic host-guest interactions is vital for designing advanced MOFs.

The researchers used computational simulations to unravel this relationship, focusing on two types of domains within MOFs: guest-adsorbed (harder) and guest-desorbed (softer). They found that the difference in elastic stiffness between these domains determined their shapes, with guest adsorption leading to compact domains and guest desorption resulting in flattened domains. By mathematically linking lattice changes to host-guest interactions, the researchers gained valuable insights into the origin of elastic heterogeneity in MOFs.

These findings have significant implications for soft porous materials. Compact domains can be useful for strong guest confinement, making them ideal for applications like gas storage. On the other hand, flattened domains increase the MOFs’ surface area, facilitating chemical reactions. This breakthrough will expedite research and development, enhancing the practical utility of MOFs in various devices, such as sensors, supercapacitors, and drug delivery tools.

Source: University of Tokyo

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