Shuhei Furukawa (left) and Gavin Craig (right) with the newly developed porous gel. Photo: Kyoto University iCeMS.
Shuhei Furukawa (left) and Gavin Craig (right) with the newly developed porous gel. Photo: Kyoto University iCeMS.

Researchers at Kyoto University in Japan have developed a new approach to controlling the fabrication of soft, porous materials, overcoming a primary challenge in materials science.

Soft, porous, gel-like materials that have a stable structure despite their tiny cavities have a wide variety of potential applications. Building insulation, energy storage devices, aerospace technologies and even environmental clean-ups can all benefit from incorporating these light and flexible materials.

Molecular assemblies known as metal-organic polyhedra (MOPs) are leading contenders for producing these materials due to their interesting shapes and porosity. But using MOPS to fabricate gel-like materials with intrinsic and controlled porosity remains a challenge.

Shuhei Furukawa at Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS), together with colleagues in Japan and Spain, has now found a way to control the synthesis of a porous gel through the self-assembly of MOPs using organic linkers.

The team started with a cuboctahedral-shaped MOP formed of rhodium atoms linked with strong carboxylate bonds, which give the MOP a high degree of structural stability. The MOPs were placed in a liquid solvent with organic 'linker' molecules to trigger the self-assembly process, producing spherical particles. By gradually adding linkers to the solution and changing the solution's temperature, the researchers were able to control the formation and size of the spherical particles.

The researchers found that subtle changes in the reaction conditions greatly influenced the outcome of the reactions. When the team added a large amount of linker molecules to the rhodium MOP solution at 80°C and then rapidly cooled it to room temperature, a gel formed. The team then treated the gel with supercritical carbon dioxide; the gas replaced the liquid component of the gel, leading to the formation of an ultralight 'aerogel'.

"We envisage that by understanding the relationship between molecular-scale geometries and the resulting macroscopic shapes, a real advance can be made towards the development of soft matter that is both permanently porous and amenable to materials processing," the researchers conclude in a paper on this work in Nature Communications. Their findings could lead to the fabrication of soft, flexible materials with permanent porosity, they say.

This story is adapted from material from Kyoto University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.