The doors that 3D printing has opened, one after the other—and at such an accelerated speed—are astounding and seemingly infinite. With incredible designs being produced in nearly every sector from architecture to aerospace, and research labs embracing the new technology everywhere to not just change the world, but literally change and save lives, it’s as if each idea and innovation builds on itself and continues to propel us further into a world of progress we simply never imagined.
And aside from the hardware and software, all mind-blowing in themselves as a rule today, what drives much of the serious innovation and breakthroughs in 3D printing is the materials themselves, and intense materials research leading to new techniques. Most people who are just being introduced to the 3D printer for the first time will ask, “What do you feed this thing?” Today, that’s a long –and often very surprising—answer, with so many new options available. The bottom line though is that what many researchers are producing on the 3D printing front, via a variety of alternate materials and new processes, is unlike anything we’ve ever seen before.
And scientists from both Kansas State University and the University at Buffalo are busy taking materials to a new level, with the development of a process that allows them to 3D print graphene oxide aerogels. While we hear a lot about graphene in 3D printing today due to its unique and conductive qualities, using that particular material for this project, led by Professor Dong Lin, and Chi Zhou, required some resourcefulness and studying, which led to a pretty complex new method. The result? Extremely lightweight aerogels (with densities ranging from 0.5 to 10mg/cm3,) which boast good electrical conductivity and high compressibility.
The whole process has been outlined in their paper—and concisely stated with the title, ‘3D Printing with Aerogels.’ Authored by Qiangqiang Zhang, Feng Zhang, Sai Pradeep Medarametla, Hui Li, Chi Zhou, and Dong Lin, the research was recently published in the Small journal.
The goal of the research is to further exploit the uses of graphene aerogels in regards to their conductivity and compressibility for use in shock damping, batteries, and catalysts. Due to their light weight, low density, and spongy texture, they can be used in thermal and optical insulation currently. And while the researchers knew they could expand on the construction and uses of these aerogels with 3D printing, that doesn’t mean it was easy.
The team had to find a new way to print with graphene, aside from traditional methods which mix in other materials first and then remove them afterward, often denigrating the structures. They also found that with 3D printing and its famous layering, it was hard to produce strong, complex structures, with overhangs being an issue as well.
“In order to print you need to change the viscosity of graphene so it’s really high,” says Dong Lin of Kansas State University.
“Although strategies have been presented to adjust viscosity of graphene ink for shear thinning and self-support, they are limited in several key qualities, namely, pure, continuous, boundary free, controlled microstructure, and truly 3D architectures (e.g., 3D truss with overhang structures),” said the researchers in their paper. “Here, we concurrently achieve these key features by coupling multinozzle drop-on-demand inkjet printing of pure graphene oxide (GO) suspension with freeze casting for rapid printing of 3D GA architectures.”
The scientists were able to create the new process by combining water with the graphene oxide. In quite a fascinating process, they printed it at -25°C and then watched as each layer actually froze during printing. The amazing result overall was that they could fabricate their structure and allow it to be supported by ice which then melted once they applied the suspension to it, with layers mixing, refreezing, and making the structure even stronger.
With the use of another nozzle filled with water, they were able to create the complexity required, manipulated both temperatures and resulting ice. They were then able to freeze dry the aerogels and in nitrogen, saying goodbye to the water and then reducing the structure to graphene.
The hope is that an entirely new class of applications will be found for these ultra-light aerogels. Not only that, but the scientists are continuing on to see if their new method, using multiple nozzles, will also be able to 3D print aerogels that consist of multiple materials. Discuss in the 3D Printed Graphene Aerogels forum over at 3DPB.com.[Source: Chemistry World]