Discovered: An easier way to create 'flexible diamonds'
Original technique predicts and guides the ordered creation of strong,
yet flexible, diamond nanothreads

Date:
March 2, 2022
Source:
Carnegie Institution for Science
Summary:
As hard as diamond and as flexible as plastic, highly sought-after
diamond nanothreads would be poised to revolutionize our world --
if they weren't so difficult to make. Recently, a team of scientists
developed an original technique that predicts and guides the ordered
creation of strong, yet flexible, diamond nanothreads, surmounting
several existing challenges. The innovation will make it easier
for scientists to synthesize the nanothreads -- an important step
toward applying the material to practical problems in the future.



FULL STORY ==========================================================================
As hard as diamond and as flexible as plastic, highly sought-after
diamond nanothreads would be poised to revolutionize our world -- if
they weren't so difficult to make.


========================================================================== Recently, a team of scientists led by Carnegie's Samuel Dunning and
Timothy Strobel developed an original technique that predicts and guides
the ordered creation of strong, yet flexible, diamond nanothreads,
surmounting several existing challenges. The innovation will make it
easier for scientists to synthesize the nanothreads -- an important step
toward applying the material to practical problems in the future. The work
was recently published in the Journal of the American Chemical Society.

Diamond nanothreads are ultra-thin, one-dimensional carbon chains, tens
of thousands of times thinner than a human hair. They are often created
by compressing smaller carbon-based rings together to form the same type
of bond that makes diamonds the hardest mineral on our planet.

However, instead of the 3D-carbon lattice found in a normal diamond,
the edges of these threads are "capped" with carbon-hydrogen bonds,
which make the whole structure flexible.

Dunning explains: "Because the nanothreads only have these bonds in one direction, they can bend and flex in ways that normal diamonds can't." Scientists predict that the unique properties of carbon nanothreads
will have a range of useful applications from providing sci-fi-like
scaffolding on space elevators to creating ultra-strong fabrics. However, scientists have had a hard time creating enough nanothread material to
actually test their proposed superpowers.



==========================================================================
"If we want to design materials for specific applications," says
Dunning, "it's essential for us to precisely understand the structure
and bonding of the nanothreads we're making. This thread directing
method really allows us to do that!" One of the biggest challenges is
getting the carbon atoms to react in a predictable way. In nanothreads
made from benzene and other six-atom rings, each carbon atom can undergo chemical reactions with different neighbors. This leads to many possible reactions competing with one another and many different nanothread configurations. This uncertainty is one of the biggest hurdles scientists
face to synthesize nanothreads where the precise chemical structure can
be determined.

Dunning's team determined that adding nitrogen to the ring in place of
carbon might help guide the reaction down a predictable pathway. They
chose to start their work with pyridazine -- a six atom ring made up
of four carbons and two nitrogens -- and began working on a computer
model. Dunning worked with Bo Chen, Donostia International Physics
Center, and Li Zhu, Assistant Professor at Rutgers and Carnegie Alum,
to simulate how pyridazine molecules behave at high pressure.

"In our system, we use two nitrogen atoms to remove two possible reaction
sites from the ring system. This dramatically reduces the number of
possible reactions," says Dunning.

After running several computer simulations showing successful nanothread formation at high pressure, they were ready to take the experiment to
the lab.



==========================================================================
The team took a drop of pyridazine and loaded it into a diamond anvil
cell -- a device that allows scientists to produce extreme pressures
by compressing samples between the tiny tips of more traditional
diamonds. Using infrared spectroscopy and X-ray diffraction, they
monitored changes in the pyridazine's chemical structure up to about
300,000 times normal atmospheric pressure looking for the creation of
new bonds.

When they saw the bonds forming, they realized they had successfully
predicted and created the first pyridazine diamond nanothread in the lab.

"Our reaction pathway produces an incredibly orderly nanothread,"
said Dunning.

"The ability to incorporate other atoms into the nanothread backbone,
guide the reaction, and understand the nanothread's chemical environment
will save researchers invaluable time in developing nanothread
technology." This process of using these non-carbon atoms to guide
the formation of nanothreads, which Dunning calls "thread directing,"
is a significant step towards a future where scientists can predictably
create these materials and use them for advanced applications. Now that
this synthetic strategy has been discovered, Dunning plans to identify
and test the many possible nanothread precursors.

He also can't wait to start putting the pyridazine nanothreads through
their paces.

Dunning concluded, "Now that we know we can make this
material, we need to start making enough to learn enough
to determine mechanical, optical, and electronic properties!" ========================================================================== Story Source: Materials provided by
Carnegie_Institution_for_Science. Note: Content may be edited for style
and length.


========================================================================== Related Multimedia:
* Diamond_nanothread_formation ========================================================================== Journal Reference:
1. Samuel G. Dunning, Li Zhu, Bo Chen, Stella Chariton, Vitali B.

Prakapenka, Maddury Somayazulu, Timothy A. Strobel. Solid-State
Pathway Control via Reaction-Directing Heteroatoms: Ordered
Pyridazine Nanothreads through Selective Cycloaddition. Journal
of the American Chemical Society, 2022; 144 (5): 2073 DOI:
10.1021/jacs.1c12143 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220302185959.htm

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