Scientists have found a new way to structure carbon at the nanoscale, creating a structure that surpasses diamond in strength-to-density ratio.
Despite the fact that the tiny carbon grid was made and tested in the laboratory, it is still very far from its practical use. But this new approach could help us create stronger, lighter materials in the future, which is of great interest to industries such as aerospace and aviation.
What we're talking about here is something known as nanolatic structures – porous structures like the one in the image above are made up of three-dimensional carbon struts and curly braces. Thanks to their unique structure, they are incredibly strong and lightweight.
Usually these nanolatics are based on a cylindrical framework (they are called beam nanolatics). But the team has now created lamellar nanolatics, structures based on tiny lamellae.
Based on experiments and calculations, the lamellar approach promises a 639% increase in strength and a 522% increase in stiffness over the nanostructured beam method.
To definitively test these materials in the laboratory, the researchers used a sophisticated 3D laser printing process called direct laser writing two-photon polymerization, which essentially uses carefully controlled chemical reactions within a laser beam to etch molds at the smallest scale.
Using a UV-sensitive liquid resin, the process emits photons onto the resin to turn it into a solid polymer of a specific shape. Additional steps are then required to remove excess resin and heat the structure to hold it in place.
What scientists have been able to do here is actually approaching the maximum theoretical stiffness and strength of this type of material – the boundaries known as the upper boundaries of Khashin-Shtrikman and Suke.
As confirmed by a scanning electron microscope, these are the first real experiments to show that theoretical ultimate strengths can be reached, although we are still far from being able to manufacture this material on a larger scale.
In fact, part of the strength of the material lies in its tiny size: when such objects are compressed to 100 nanometers – a thousand times less than the thickness of a human hair – the pores and cracks in them become smaller and smaller, reducing potential defects.
As far as how these nanolatics can ultimately be used, they will certainly be of interest to the aerospace industry – the combination of strength and low density makes them ideal for aircraft and spacecraft.
The research was published in Nature Communications.
Sources: Photo: (Cameron Crook and Jens Bauer / UCI)
