www.3ders.org

Feb. 12, 2015 | By Alec

While most commercial 3D printers are limited to filament, many manufacturing experts believe that the technology’s creative potential is largely found in other materials with more applications and properties. Resin and particularly metals can after all be used for a lot more objects and components. But of all those different types of ‘filament’, graphene should perhaps be seen as the holy grail of manufacturing. It’s therefore very exciting to hear that a team of London-based engineers have successfully experimented with graphene 3D printing.

For those of you who’ve never heard of graphene, it is essentially a form of carbon, just like diamonds or the lead in pencils. But unlike most forms of carbon, it isn’t a type of 3D shape, but is instead a 2D material that consists of a hexagonal sheet only a single atom thick. But its properties are especially interesting; not only is it very light and flexible, it is also extremely durable (about a hundred times stronger than steel) while being a very efficient conductor of heat and electricity. Its theoretical existence has been discussed for decades, but it was only first successfully produced in 2004, and has been very interesting to manufacturers since then.

The structure of graphene on atomic level.

It is currently especially used in the manufacturing of electronics, batteries and so on, but engineers have been looking for 3D fabrication methods for years now; a development crucial towards making it applicable for a far wider range of manufacturing. But it now looks like that method has been discovered by a team from the Department of Materials at the Imperial College in London, consisting of drs Esther Garcia Tunon Blanca, Suelen Barg, Victoria Garcia Rocha and Professor Eduardo Saiz Gutierrez, working together with teams from the University of Warwick, the University of Bath, and the Universidad de Santiago de Compostela.

The technique they’ve developed, which is extensively explained in an article entitled Printing in Three Dimensions with Graphene (published in the journal Advanced Materials in January), essentially consists of FDM 3D printing.

To explain, production of graphene objects requires the precise patterning of graphene hexagonal shapes. To make this possible, the Imperial College team has developed a type of ‘FDM filament’ consisting of flakes of chemically modified graphene mixed with a type of responsive polymer (a polymer that can be induced to trigger a certain behaviour). In this case, it ensures that the graphene parts have the right level of viscoelasticity, while also bonding it to previous or following layers.

Originally, the goal was to 3D print complete graphene structures, rather than composites. This might have been possible in a water-based system, but as Esther García-Tuñon Blanca, who headed the study, explained, that wasn’t possible. "Graphene is very hydrophobic so it is not possible to formulate a water-based ink directly. The researchers therefore used chemically modified graphene – also known as graphene oxide (GO) – instead. GO can be processed in water to build the desired architectures."

In a nutshell, it thus functions like plastic filament. As García-Tuñon Blanca told reporters: "Our formulations have the flow and physical properties we need for the filament deposition process required in 3D printing: They need to flow through very small nozzles and set immediately after passing through it, retaining the shape and holding the layers on top,’ she says. ‘We use this two-dimensional material as building block to create macroscopic 3D structures and a technique called direct ink writing (DIW) also known as direct write assembly (DWA), or Robocasting."

And its looking very promising. The graphene ‘filament’ can be 3D printed with extrusion nozzles as thin as 100 µm already, while García-Tuñon  feels it can also be modified for other 3D printing setups. Once 3D printed into structures, the graphene creation is thermally treated to ensure it has all the highly potent properties of graphene. After that, these prints can be manipulated in various ways, such as through chemicals or electrochemical reduction, and still keep those graphene properties.

3D printed graphene under the microscope.

The study thus appears to be very successful, though García-Tuñon notes that "there are still many challenges to overcome in both Additive Manufacturing and graphene technologies. […] There is still a long way to go from here to the use of 3D printing for a wide variety of materials in multicomponent and practical devices."

As part of that development, the team behind this grahene filament is currently looking at specific applications, such as flexible electronics. They have also teamed up with Imperial Innovations to explore a commercialization path for their 3D printable graphene. As part of that process, several industrial partners have already been approached to develop applications. One plan already in the works is 3D printed graphene ‘skin’ for robotic structures.

With this study, the future of industrial 3D printing just got a little brighter. Could this ‘super filament’ be the key to widespread adoption? For more, take a look at this brief interview with García-Tuñon below:

 

Posted in 3D Printing Technology

 

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