A new method makes it possible to 3D-print objects in graphene with a resolution much smaller than was previously possible. Thanks to this low resolution, graphene can theoretically be 3D-printed in any shape and size.
The method was developed by researchers at Virginia Tech and the Lawrence Livermore National Laboratory. Graphene is a promising material with remarkable properties. For instance, graphene is the strongest material ever discovered on Earth and has high electrical and thermal conductivity.
What is graphene?
Graphene consists of a single layer of carbon atoms arranged in a hexagonal lattice. If several layers of graphene are stacked on top of each other to create a three-dimensional shape, graphite is created, which is used in pencils, among other things. However, this material does not contain the very properties that make graphene so attractive.
It has long been possible to 3D-print graphene. In this process, layers of graphene are separated from each other using small pores filled with air. The resulting porous graphene structure is called a graphene aerogel.
Only suitable for simple objects
However, the graphene aerogels available until now had their limitations. For example, objects using these materials could only be printed at a low resolution, which meant that only simple objects without complex shapes could be created in graphene. "Using this technique, only very limited structures can be created, as there is no support and the resolution is very limited. As a result, you cannot create free forms."
However, researchers from Virginia Tech and the Lawrence Livermore National Laboratory report having developed a new 3D printing method that allows graphene to be printed at a higher resolution. This theoretically makes it possible to print graphene in any shape and size.
"A designer can now create a three-dimensional topology consisting of interconnected graphene layers," explains Xiaoyu "Rayne" Zheng, assistant professor in the Department of Mechanical Engineering in the College of Engineering and director of the Advanced Manufacturing and Metamaterials Lab at Virginia Tech. "This new design and manufacturing freedom will lead to optimisation of strength, conductivity, mass transport and weight density that is not achievable in graphene aerogels."
Porous hydrogel from graphene oxide
Zheng developed the printing method together with third-year Macromolecular Science and Mechanical Engineering student Ryan Hensleigh. The material used was developed by Hensleigh by creating a porous hydrogel from graphene oxide. This hydrogel was then broken up using ultrasound, after which light-sensitive polyacrylate was added to it.
This combination makes it possible to create solid 3D structures using micro-stereolithography. In this process, graphene oxide is trapped in long and rigid chains of polyacrylate. The 3D structure created is then placed in an oven to burn the polymers and melt the object together. The end result is a pure and lightweight graphene aerogel.
Much smaller resolution
Hensleigh points out that his printing method makes it possible to create objects with a much smaller resolution, allowing the objects to contain more detail. According to the student, other processes allow printing to an accuracy of 100 microns, while the new method allows for a resolution of 10 microns.
More information can be found in a paper published by Zheng and Hensleigh in Materials Horizon.
Author: Wouter Hoeffnagel
Source: Virginia Tech
Source: Paper 'Additive manufacturing of complex micro-architected graphene aerogels'
Source Photo: Pixabay / seagul
