from the tiny-prisoners-beware dept.
For decades, scientists have been trying to make a true molecular chain: a repeated set of tiny rings interlocked together. In a study in Science published online Nov. 30, University of Chicago researchers announced the first confirmed method to craft such a molecular chain.
Many molecules described as "linked" are joined with fixed covalent bonds—not two freely moving interlocked rings. The distinction makes a big difference when it comes to how the chain moves.
"Think about dangling a silver chain onto your palm: It collapses easily into a flat pool and can flow off your hand, much different from a string of fixed beads," said Stuart Rowan, a professor at UChicago's Institute for Molecular Engineering and Department of Chemistry and lead author on the paper.
The longer interlocked chains could make materials or machines with intriguing properties, researchers said. Polymers—materials made of repeated units joined together—are extremely useful in everyday life, making up everything from plastics to proteins; and this new way to combine the repeat units could open new avenues in engineering.
[...] "A metal rod is rigid, but a metal chain made of the same material is very flexible," said UChicago postdoctoral researcher Qiong Wu, the first author on the paper. "By keeping the same chemical composition but changing the architecture, you can dramatically change the material's behavior."