By Cory Nealon
Graphene is a wonder material saddled with great expectations. Discovered in 2004, it is one million times thinner than a human hair, 300 times stronger than steel and is the best known conductor of heat and electricity. These qualities could, among other things, make computers faster, batteries more powerful and solar panels more efficient.
Another option is to use a 3-D printer. In this scenario, scientists typically mix graphene with a polymer or other thickening agent. This helps keep the structure from falling apart. But when the polymer is removed via thermal process, it damages the delicate structure.
However, the material is difficult to manipulate beyond its two-dimensional form.
A research team comprised of engineers from UB, Kansas State University and the Harbin Institute of Technology in China may have solved that problem.
A study published in the journal Small describes how the team used a modified 3-D printer and frozen water to create lattice-shaped cubes and a three-dimensional truss with overhangs using graphene oxide. The structures could be an important step toward making graphene commercially viable in electronics, medical diagnostic devices and other industries.
“Graphene is notoriously difficult to manipulate, but the structures we built show that it’s possible to control its shape in three- dimensional forms,” said Chi Zhou, an assistant professor of industrial and systems engineering and a member of the Sustainable Manufacturing and Advanced Robotic Technologies (SMART) Community of Excellence.
In their experiments, the research team mixed the graphene oxide with water. They then printed the lattice framework on a surface of -25°C. The graphene is sandwiched between the layers of frozen ice, which act as a structural support.
After the process is completed, the lattice is dipped in liquid nitrogen, which helps form even stronger hydrogen bonds. The lattice then is placed in a freeze dryer, where the ice is changed into gas and removed. The end result is a complex, three-dimensional structure made of graphene aerogel that retains its shape at room temperature.
The researchers plan to build on their findings by investigating how to create aerogel structures formed of multiple materials.
In addition to Zhou, authors include Qiangqiang Zhang and Hui Li, students at Harbin, Feng Zhang, a student at UB, and Dong Lin, assistant professor, and Sai Pradeep Medarametla, a student, both from Kansas State University.
The research team also received support from UB faculty members Mark Swihart, Distinguished Professor of Chemical and Biological Engineering and director of the New York State Center of Excellence in Materials Informatics, and Jonathan Lovell, assistant professor of biomedical engineering.