Ultra-thin 'diamond nanothreads' developed
22 Sep 2014
Almost a century after it was first attempted, scientists have successfully compressed separate carbon-containing liquid benzene molecules into a diamond-like material.
Chemists at Penn State University, US have, for the first time, discovered how to produce ultra-thin diamond nanothreads that could exhibit strength and stiffness far greater than that of today’s strongest nanotubes and polymers.
A full account of the study has been published in the journal Nature Materials.
“It is as if an incredible jeweller has strung together the smallest possible diamonds into a long miniature necklace
PSU chemist John V. Badding
According to research team leader John V. Badding, the nanothread has a structure that has never been developed before.
The nanothread’s core features a long, thin strand of carbon atoms arranged in a configuration similar to the fundamental unit of a diamond’s structure.
“It is as if an incredible jeweller has strung together the smallest possible diamonds into a long miniature necklace,” Badding said.
To compress the liquid molecules, the US team used the large high-pressure Paris-Edinburgh device at Oak Ridge National Laboratory to compress a 6 millimetre-wide amount of benzene.
Study co-author Malcolm Guthrie said: “We discovered that slowly releasing the pressure after sufficient compression at normal room temperature gave the carbon atoms the time they needed to react with each other and to link up in a highly ordered chain of single-file carbon tetrahedrons, forming these diamond-core nanothreads.”
According to researchers, during the compression process, flat benzene molecules stack together, bend, and break apart. Then, as the pressure is slowly released, the atoms reconnect in an entirely different yet very orderly way.
“It really is surprising that this kind of organisation happens,” Badding said.
“That the atoms of the benzene molecules link themselves together at room temperature to make a thread is shocking to chemists and physicists. Considering earlier experiments, we think that, when the benzene molecule breaks under very high pressure, its atoms want to grab onto something else but they can’t move around because the pressure removes all the space between them. This benzene then becomes highly reactive so that, when we release the pressure very slowly, an orderly polymerisation reaction happens that forms the diamond-core nanothread.”
Although Badding believes the new material could be used to help protect the atmosphere, through the development of lighter, more fuel-efficient, and therefore less-polluting vehicles, he also has far more ground-breaking expectations.
“One of our wildest dreams for the nanomaterials we are developing is that they could be used to make the super-strong, lightweight cables that would make possible the construction of a ’space elevator’, which so far has existed only as a science-fiction idea,” Badding said.
