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New type of strong, lightweight 3D graphene material
Agroup of researchers from MIT developed one of the create them using conventional manufacturing. For testing
strongest, yet lightweight materials known today, by purposes, the team used 3D printed models of the gyroids,
compressing and fusing flakes of graphene. Graphene, thought enlarged to thousands of times their natural size, and
to be one of the strongest of all known materials, is a two- created with a high-resolution, multi-material 3D printer.
dimensional form of carbon, touted as a “wonder material,” In order to find the answer, the team subjected the 3D
models to several mechanical tensile and compressive tests,
and is notoriously difficult using their theoretical models to simulate the mechanical
to make in large quantities. response under loading. Those results were compared to
Until now, researchers have computational simulations that mimic the loading conditions
had a tough time turning its in a tensile loading machine. In this simulation, Qin said
two-dimensional strength that “one of our samples has 5% the density of steel, but 10
into three-dimensional times the strength.”
materials. But MIT’s newly
designed material, a The experiment and simulation results matched: Buehler
sponge-like configuration of explained that their 3D graphene material, made up of
graphene, can be ten times curved surfaces under deformation, reacts like sheets of
stronger than steel, with a density of just five percent The paper. Paper can be easily crumpled, because it’s not strong
MIT research team’s findings were reported recently in the along its width and length. But when paper is rolled into a
journal Science Advances. The paper was co-written by Markus tube, the strength along the tube’s length is much higher.
Buehler, McAfee Professor of Engineering and the head of MIT’s The geometric arrangement of the graphene flakes after
Department of Civil and Environmental Engineering (CEE); treatment makes a similar strong configuration.
CEE research scientist Zhao Qin; graduate student Gang Seob
Jung; and Min Jeong Kang Meng, class of 2016. Their findings, The results, which are based on the team’s “atomistic
according to MIT, reveal that “the crucial aspect of the new computational modeling,” ruled out the notion that it could
3D forms has more to do with their unusual geometrical be feasible to make structures out of 3D graphene that
configuration than with the material itself, which suggests could actually be lighter than air, and used as a replacement
that similar strong, lightweight materials could be made from for helium in balloons, because at densities that low, the
a variety of materials by creating similar geometric features.” new material would collapse from air pressure. But there
are other possible applications for this strong, lightweight
The MIT research team was able to assemble a mathematical material. Buehler suggests that one could potentially use
framework that comes very close to matching experimental either the “real graphene material or use the geometry we
observations, by analyzing the behavior of the graphene discovered with other materials, like polymers or metals,”
structure down to the level of the individual atoms. 2D in order to gain similar advantages of strength combined
materials are, in essence, flat sheets that are only one atom with cost or processing method advantages, or even material
in thickness. They are extremely strong, and possess unique properties like electrical conductivity
electrical properties, but, according to Buehler, because of
their inherent thinness, “they are not very useful for making The team explained that, for actual synthesis, it’s possible to
3-D materials that could be used in vehicles, buildings, or use polymer or metal particles as templates, use a chemical
devices.” The team produced a stable, strong structure that vapor deposit before heat and pressure treatments to cover
resembles corals and microscopic creatures known as diatoms, them with the graphene, and then remove the polymer or
by using a combination of heat and pressure to compress small metal in order to keep the 3D graphene in the gyroid shape.
flakes of graphene. The resulting shapes have a huge surface This porous geometry could be used when building large
area in proportion to their volume, and are extraordinarily structures, like a concrete bridge; it would even provide
strong. They look sort of like Nerf balls – they are rounded good insulation for the bridge, due to the amount of enclosed
objects, but full of holes. These complex shapes are known airspace. Since the gyroid is full of tiny pore spaces, it could
as gyroids, and Buehler said that it’s “probably impossible” to even be used in some filtration systems.
• January 2017 • Plastics News 64
