Graphene as 3D printed aerogels
A 3D printing technique for the fabrication of graphene aerogels with complex microstructures will create novel uses for the ‘wonder material’.
Aerogels are sponge-like, low density materials with numerous applications including thermal and optical insulators. Graphene aerogels continue to interest innovators and researchers due to their high compressibility and conductivity properties.
3D printing is just one of the promising methods for the creation of graphene aerogels with intricate architectures. Not being a simple procedure, however, researchers have to mix graphene with polymers or silica before inkjet printers can shape it using high temperatures. The polymer or silica is then extracted, using either burning or chemical processes, which can damage the aerogel’s structure.
Another technique used by researchers at Kansas State University, USA, allowed them to overcome these problems. Graphene oxide was mixed with water and printed on a surface at low temperatures (-25°C) where each layer froze as it was printed, enabling a graphene oxide structure reinforced by ice. When depositing the graphene oxide suspension onto the frozen structure, however, they found that the unfrozen material melted it. When these layers were mixed freely, they refroze, forming hydrogen bonds and improving the structural integrity. By using a second printer nozzle filled with pure water, they could also create complex structures, as the ice continued to reinforce them.
Andrea Ferrari, director of the graphene centre at the University of Cambridge, UK, said: ‘It’s certainly an interesting technique. Additive manufacturing is quite widespread for prototyping and it is good to have graphene available to do this type of work.’
The researchers now hope to improve their technique with multi-nozzle methods creating aerogels and structures with multiple materials.
