Researchers developed a new approach control the self-assembly of molecules leading to the formation of an ultralight, porous gel, according to a study published on July 12, 2018.
This study was conducted by the researchers at the Kyoto University. Molecular assemblies known as metal-organic polyhedra (MOPs) are leading contenders for these materials, owing to interesting shapes and porosity of these molecular assemblies. However, until now, fabrication of materials from these assemblies maintaining intrinsic and controlled porosity was a huge challenge. Shuhei Furukawa of Kyoto University along with colleagues in Japan and Spain discovered a method to control the synthesis of a porous gel through the self-assembly of MOPs using organic linkers.
Initially, a cuboctahedral-shaped MOP made of rhodium atoms that was linked with strong carboxylate bonds was used. This carboxylate bonds gave a high degree of structural stability to the MOP. Furthermore, the MOPs were placed in a liquid solvent with organic ‘linker’ molecules to trigger the self-assembly process. Researchers observed that the addition of linkers to the solution and change in temperature of the solution allowed them to control the formation and size of the spherical particles that were developed.
It was found that subtle changes in the reaction conditions had influenced the outcome of the reactions. A gel was formed when large amount of linker molecules were added to the rhodium MOP solution at 80°C and then rapidly cooled it to room temperature. The gel was then treated with supercritical carbon dioxide, which replaced the liquid component of the gel and resulted in the formation of an ultralight aerogel.
Researchers said, “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.”