Imagine if you could unspool a diamond like a ball of yarn, pulling out microscopic threads of the hardest substances on Earth and 20,000 times thinner than a strand of hair. As it turns out, you can do exactly that—with a little bit of equipment.
Last year, scientists at Penn State University found a way to create tiny diamond nanothreads, or super strong chains of atoms that are identical to those of diamonds. A funny thing happens when you exert 200,000 times the pressure of the atmosphere on liquid benzene and then slowly remove it: the benzene turns into tiny chains, consisting of four linked carbon atoms each—replicas of the exact rings of carbon that make up diamonds.
Now, a team from the Queensland University of Technology in Australia modeled the threads using large-scale molecular dynamics simulations, and found that the diamond nanothreads actually hold up incredibly well when under the conditions of the model, and can be used to create strong but flexible three-dimensional nano-architectures. The new simulation, published earlier this month, has reinvigorated hope about the promising aerospace properties of what might be the world’s strongest substance.
In order to produce these chains in the first place, the Penn State researchers used a large machine called a Paris-Edinburgh device at Tennessee's Oak Ridge National Laboratory last month. They used a 6-millimeter wide quantity of liquid benzene, much larger than similar experiments have used before.
In past experiments, applying pressure to liquid benzene has resulted in a polymer that’s ambiguous and doesn’t hold a shape. But with the larger quantity, the scientists were forced to release the pressure much more slowly. This, it turns out, was the secret: the carbon atoms snapped into a tetrahedral structure, meaning that they were each connected to four others. The result, after the molecules had polymerized, was a series of diamond crystals, capped with a hydrogen atom.
These ultra-strong diamond nanothreads could come in handy as an alternative to carbon nanotubes, cylindrical carbon molecules with walls of graphene that are used in nanotechnology, optics, and electronics. But the most exciting potential use for diamond nanothreads is something much more otherworldly: building a ladder to space.
One of the biggest challenges limiting space exploration is the need to constantly return to Earth’s atmosphere for supplies, food and equipment, as well as the prohibitive cost of sending rockets through the atmosphere. Way back in 1895, a Russian rocket scientist named Konstantin Tsiolkovsky came up with a brilliant solution: the space elevator.
A space elevator, put simply, is a giant, 60,000-mile cable tethered to the Earth's equator that reaches through the atmosphere and out into space on the other side. At the end of the cable, far past the satellites in orbit, is a counterweight maintaining tension. A device called a “climber” could be used to ferry cargo from the planet’s surface to its orbit and beyond.
But a cable this long and this important would have to be made of the strongest stuff on Earth, literally. Researchers think that diamond nanothreads could be that stuff. One of the researchers on the most recent paper even called them an “ideal” material for this type of project.
The prospect of a space elevator isn’t as far away as it sounds, either. One Tokyo-based construction company called Obayashi, has already announced plans to build one by 2050. If all goes as planned, diamond nanothreads could be leading the way there.