Researchers develop novel process to 3D print one of the strongest
materials on Earth
August 27, 2018
from Virginia Tech and Lawrence Livermore National Laboratory have
developed a novel way to 3D print complex objects of one of the
highest-performing materials used in the battery and aerospace
Previously, researchers could only print this material, known as
graphene, in 2D sheets or basic structures. But Virginia Tech engineers
have now collaborated on a project that allows them to 3D print graphene
objects at a resolution an order of magnitude greater than ever before
printed, which unlocks the ability to theoretically create any size or
shape of graphene.
Because of its strength - graphene is one of the strongest materials
ever tested on Earth - and its high thermal and electricity
conductivity, 3D printed graphene objects would be highly coveted in
certain industries, including batteries, aerospace, separation, heat
management, sensors, and catalysis.
Researchers from the Virginia Tech
College of Engineering and Lawrence Livermore National Laboratory have
developed a novel process to 3D print graphene, one of the strongest
materials ever tested, at a higher resolution that was an order of
magnitude greater than ever printed before.
Graphene is a single layer of carbon atoms organized in a hexagonal
lattice. When graphene sheets are neatly stacked on top of each other
and formed into a three-dimensional shape, it becomes graphite, commonly
known as the "lead" in pencils.
Because graphite is simply packed-together graphene, it has fairly poor
mechanical properties. But if the graphene sheets are separated with
air-filled pores, the three-dimensional structure can maintain its
properties. This porous graphene structure is called a graphene aerogel.
"Now a designer can design three-dimensional topology comprised of
interconnected graphene sheets," said Xiaoyu "Rayne" Zheng, assistant
professor with the Department of Mechanical Engineering in the College
of Engineering and director of the Advanced Manufacturing and
Metamaterials Lab. "This new design and manufacturing freedom will lead
to optimization of strength, conductivity, mass transport, strength, and
weight density that are not achievable in graphene aerogels."
Zheng, also an affiliated faculty member of the Macromolecules
Innovation Institute, has received grants to study nanoscale materials
and scale them up to lightweight and functional materials for
applications in aerospace, automobiles, and batteries.
Previously, researchers could print graphene using an extrusion process,
sort of like squeezing toothpaste, but that technique could only create
simple objects that stacked on top of itself.
"With that technique, there's very limited structures you can create
because there's no support and the resolution is quite limited, so you
can't get freeform factors," Zheng said. "What we did was to get these
graphene layers to be architected into any shape that you want with high
This project began three years ago when Ryan Hensleigh, lead author of
the article and now a third-year Macromolecular Science and Engineering
Ph.D. student, began an internship at the Lawrence Livermore National
Laboratory in Livermore, California. Hensleigh started working with
Zheng, who was then a member of the technical staff at Lawrence
Livermore National Laboratory. When Zheng joined the faculty at Virginia
Tech in 2016, Hensleigh followed as a student and continued working on
To create these complex structures, Hensleigh started with graphene
oxide, a precursor to graphene, crosslinking the sheets to form a porous
hydrogel. Breaking the graphene oxide hydrogel with ultrasound and
adding light-sensitive acrylate polymers, Hensleigh could use projection
micro-stereolithography to create the desired solid 3D structure with
the graphene oxide trapped in the long, rigid chains of acrylate
polymer. Finally, Hensleigh would place the 3D structure in a furnace to
burn off the polymers and fuse the object together, leaving behind a
pure and lightweight graphene aerogel.
a significant breakthrough compared to what's been done," Hensleigh
said. "We can access pretty much any desired structure you want." The
key finding of this work, which was recently published with
collaborators at Lawrence Livermore National Laboratory in the journal
Materials Horizons, is that the researchers created graphene structures
with a resolution an order of magnitude finer than ever printed.
Hensleigh said other processes could print down to 100 microns, but the
new technique allows him to print down to 10 microns in resolution,
which approaches the size of actual graphene sheets.
"We've been able to show you can make a complex, three-dimensional
architecture of graphene while still preserving some of its intrinsic
prime properties," Zheng said. "Usually when you try to 3D print
graphene or scale up, you lose most of their lucrative mechanical
properties found in its single sheet form."