UC Berkeley researchers weave organic threads into molecular framework

Lu Ding/Courtesy

Related Posts

Easily taken for granted as a simplistic art form, weaving remains one of the most elegant means of producing durable materials — and scientists are only beginning to realize its potential in areas ranging from clean energy applications to electronics manufacturing.

An international team of scientists affiliated with the Lawrence Berkeley National Laboratory and UC Berkeley recently discovered how to produce structurally dynamic materials by weaving microscopic threads into molecular structures called covalent organic frameworks, or COFs. The technique has never been implemented on such a minuscule level before, said Omar Yaghi, co-director of the Kavli Energy NanoSciences Institute, campus chemistry professor and an author of the study.

“What this study really demonstrates is that it’s a new way of making materials,” Yaghi said. “It’s no surprise that weaving is the oldest method of making robust yet elastic, dynamic materials.”

Research contributors published a report detailing the research in Science, an academic journal, on Jan. 22.

COFs are porous, three-dimensional crystals ideal for storing large amounts of molecules. Invented by Yaghi in 2005, COFs were originally composed of “organic building blocks” stitched together by strong covalent bonds, forming a net. The newly-designed COF-505 model, however, uses a copper ion framework, which can be removed without affecting the basic structure of the COF.

“You can imagine this material as a kind of fabric that is so soft that you can wear it, but at the same time robust enough that you won’t break it,” said Yuzhong Liu, a doctoral candidate in the campus chemistry department.

The researchers also redefined material synthesis methods by uniting molecules via mechanical — rather than chemical — bonds. Weaving organic threads in an “up and down” fashion gives traditionally rigid materials versatility and allows scientists to fuse unrelated compounds together.

According to scientists involved with the project, the effects could be far-reaching. Christian Diercks, a UC Berkeley professor in the department of chemistry, notes that because the COFs are made from “molecular building blocks,” they can be structurally altered by scientists more easily than other crystalline structures. Hiroyasu Furukawa, an assistant researcher on the project, said in an email that scientists can now rework COF structures to suit different purposes, providing new opportunities for researchers in chemistry, physics and engineering.

Liu predicted that future COF designs could be created to allow the COFs to transition between different elasticity states with light triggers rather than by manually removing the copper ion framework.

Yaghi believes the new COF design highlights the potential for scientific discovery to improve pre-existing systems and open doors to new ideas.

“If you can think it and imagine it, it should be possible to make,” Yaghi said. “That’s why this report is exciting — it shows that with a slight twist in thinking, you can make something people thought could not be made.”

Kimberly Nielsen covers research and ideas. Contact her at [email protected].