From the University of Nevada, Reno to the moon

Sid Pathak and his students’ work on carbon nanotubes will soon grace the lunar surface

From the University of Nevada, Reno to the moon

Sid Pathak and his students’ work on carbon nanotubes will soon grace the lunar surface

Look to the moon one night in the near future, and among the shiny sea of gray, a speck of a speck, imperceivable to the human eye, will be the work of Siddhartha (Sid) Pathak, University of Nevada, Reno assistant professor of Chemical and Materials Engineering, and two of his undergraduate students, Cordero Nuanez and Cayla Harvey.

Pathak and his students have been conducting research on carbon nanotubes, known as CNTs, cylindrical nanostructures roughly 10,000 times smaller than a human hair.

"The scientific importance of this project is that individual carbon nanotubes are known to be the strongest material available, but they're very strong only in tension," Pathak said. "These structures are very thin and long, which means that if you compress them they buckle almost immediately. So the goal of this project was to figure out if we can get any appreciable strength of carbon nanotubes in compression."

Since individual carbon nanotubes are pretty weak in compression, Pathak and his students decided to study layers of vertically aligned CNTs, known as CNT brushes, forests or arrays. Such arrays contain tens of thousands of CNTs, all aligned vertically like trees in a forest. They used a particular CNT synthesis technique - known as carbide-derived carbon synthesis - to produce nanotube brushes of very high density, 10 times denser than any other kind of CNT arrays. The higher density means that the nanotubes in this array are very closely spaced making them ideal for intertube bridging or connecting them with multiple bridges.

Pathak's research group were able to achieve such intertube bridging using gallium ion irradiation in a focused ion beam. By compressing these nanotube bundles, Pathak and his students were able to demonstrate a strong mechanical response from the nanotubes, similar to what has been seen in tension. These remarkable results open up a wide list of potential applications for these CNTs such as: components of highly compliant thermal contacts for micro-electro-mechanical-systems and microelectronics, dry adhesives, thermally robust energy dissipating rubber and energy absorption or impact mitigation.

Their experiments also generated compelling and beautiful microscopic images. Looking at them, they knew they had something special.

"We had submitted these images to a number of art competitions," Pathak said. "Science as Art, and to cover pages of journals like ‘Materials Today.'"

Nuanez in particular was struck by the beauty of what he saw.

"When he first showed me them I was just like ‘can I just look at images?'" Nuanez said. "‘I don't want to analyze data. I'd rather just look at images.'"

As beautiful as those images were, nobody involved in the project anticipated that their work would be sought out for inclusion in the MoonArk project, a capsule filled with nanoforms and micro-scales of art and artifacts designed to showcase human achievements in areas like architecture, music, drama and poetry.

The MoonArk is the brain child of Carnegie Mellon University roboticist and research professor William L. "Red" Whittaker, and it will soon use a rover launched by the university's robotics institute to send Pathak, Nuanez and Harvey's work to the moon in the capsule.

As exciting as it is to see their work bound for the lunar surface, Pathak and his students have kept a humble perspective on the accomplishment.

"It's exciting it's going to the moon," Pathak said, chuckling. "But I don't know exactly who will see it on the moon."

"I'd rather go to the moon than the project, but that's just me," Nuanez said.

In addition to the Ark heading to the stars, a duplicate Ark is being created for exhibition on Earth.

"I think going to the moon seems like such an abstract idea since no one will see it," Harvey said. "But it's great that the science is kind of being integrated into society and that it will be displayed in exhibitions, and it's exciting to know that I was involved with it."

Pathak echoes his student's sentiments.

"Going to the moon is a cherry on the cake. But the cake is the one that we are more excited about, the science part of this work, the fact that we are actually getting the manuscript ready for submission right now, and hopefully it will be published and heavily cited," Pathak said. "Without the cake the cherry would not be there."

Pathak also took time to acknowledge the international collaboration that led to these impressive results.

"It's important not to forget our collaborators who helped in this work. Professor Yury Gogotsi's lab in Drexel University, Philadelphia helped us in synthesizing the CDC-CNT samples. We also had a lot of help in performing the compression tests from Dr. Johann Michler who works at the Swiss Federal Laboratories for Materials Science and Technology, and Dr. Nathan Mara and Dr. William Mook at Los Alamos National Laboratory, New Mexico."

As happy as he is to see his work go to the moon, Nuanez's eyes really light up when he talks about the impending publication of the work he has contributed to.

"I'm so happy that we're going to be published; we're going to be cited," Nuanez said. "I'm part of the scientific world now - that's how I look at it. This is a foot in the door. My name is on the paper that is going to be published in a great journal and people are going to know that I helped with it. That right there is just amazing."

Harvey sees the value in both the art and the science, and believes that interest in one may serve as a gateway to interest in the other.

"I think it's great, because you can look at the pictures from a scientific perspective and think ‘okay, what's happening here? What material is this?'" Harvey said. "Or if you know nothing about it, it's still visually interesting and just more abstract. It may get more people interested in the science."

With the publication of their work just around the corner and its launch into space looming on the horizon, Pathak, Nuanez and Harvey are eager for it to both enter and depart this world.

"Everybody is very excited at this point. Nobody expected the moon thing to happen," Pathak said. "We were thinking of a very nice publication coming out of this, but now we have a little bit more."

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