Many scientists consider graphene to be one of the most potentially useful materials ever created. The atom-thick chain of carbon atoms are strong, light, and promise many applications, from energy storage to pollution removal to waterproof coating.
While graphene has been studied since the 1940s, scientists have had considerable trouble constructing it into a structurally useful form on a three-dimensional level. But now, scientists at MIT have figured out how to build up graphene into useful, 3-D shapes with the potential to be lighter and stronger than steel.
The new research marks an important step forward for the material. The hexagonal structure is essentially an “unrolled” carbon nanotube only an atom thick, usually only functional on a two-dimensional level. Despite this limitation, graphene is more than 100 times stronger than steel, and converting that two-dimensional strength into a structure usable for three-dimensional building materials has for years been something of a holy grail for graphene researchers. And now, scientists may be one step closer to that conversion.
The journal Science Advances published the results of the MIT study, describing how the researchers created a porous, three-dimensional graphene material. During the synthesis of the graphene, the team added heat and pressure in order to compress small flakes of graphene together, creating complex spongelike structures similar to corals and diatoms, a kind of unicellular algae. These structures, while not very dense, have a large surface area and are extremely strong; one graphene sample had only 5 percent of the density of steel, but was 10 times stronger.
The researchers had hoped that they might be able to create useful graphene structures that would actually be lighter than air, but computer modeling at an atomic level found that such structures would be crushed by outside air pressure. But the scientists did create scaled-up 3D-printed models of complex geometric structures called gyroids that could theoretically form the basis of a new class of super-strong and lightweight materials that would not even be necessarily limited to graphene.
“You can replace the material itself with anything,” Markus Buehler, lead author of the study, said in a statement from MIT. “The geometry is the dominant factor. It’s something that has the potential to transfer to many things.”
Theoretically, a graphene designed with these gyroid shapes on a microscopic level could be even stronger than the strongest porous graphene material the team was able to create.
“Once we created these 3-D structures, we wanted to see what’s the limit — what’s the strongest possible material we can produce,” Zhao Qin, study co-author, said in the statement.