World's lightest material

Although 99.9 percent of Aerographite is made of air, the new material gets its strength from a three-dimensional carbon network. Aerographite is 75 times lighter than Styrofoam.

It was discovered by chance by PhD student, Matthias Mecklenburg in September 2010. Mecklenburg is part of Hamburg's cluster of excellence called Integrated Material Systems. He could tell that his finding was a world first.

Since then, he and his mentor, Professor Karl Schulte of Hamburg University, and colleagues under Professor Rainer Adelung at the Christian Albrechts University in Kiel, have been working toward presenting the material to the world. Their results have been published in the July issue of the journal, Advanced Materials.

DW spoke to Professor Karl Schulte about Aerographite, the world's lightest material.

DW: What's so special about Aerographite?

Professor Karl Schulte: The material is a carbon-based material. And this carbon-based material has a graphite-like structure. It is highly porous and therefore forms a three-dimensional carbon network. That makes it so light and gives it some specific properties.

And you've said that this material is almost entirely made of air because of the structure.

Yes, you can say that. Because it's so light, this means we have the air, and inside and around the air we have the structure of the carbon. You can describe it like the Eiffel Tower.The Eiffel Tower is a light-weight structure because you have all these various bars connected together and all you have in between is air. If it had been made of a massive material, it would have weighed much more.

Now, you've called your material Aerographite. It is said to be better than an earlier material, Aerogel. Can you tell us how you came to discover this because it was not what you had set out to do, was it?

We were studying some three-dimensional material. This material had been produced at Kiel University by a group headed by Professor Rainer Adelung. They had formed a zinc-oxide material which was three-dimensional in structure, but it was a massive material. We both came together and decided to try to put it into a reactor, where we could grow carbon tubes onto it. Then, we looked into the reactor and saw that part of the zinc-oxide had disappeared. But at those locations, where the zinc-oxide once was, we found a very small area covered with a see-through material. Later, through further investigation, we found that this was a carbon-like material, and then later still we found it had a graphite structure. So, the old material just disappeared and we had [in its place] this carbon structure.

So, it was a pleasant surprise. Give us an idea of what this material can be used for because as you say it is incredibly light, it's incredibly strong, but it can also be scrunched up, as far as I understand.

Yes, it is light, and in that sense it is incredibly strong - not as the total material but only due to the fact that you have the carbon, there where you have the carbon bond, [those bonds] are very strong. However, the main material and the graphite structures, they are very thin. That means it's a flexible material, with a sufficient strength, and - what's very important - it also has electrical conductivity. So, our first idea was, and is still, to use this material for batteries. With Lithium-ion batteries, you could make them lighter or you could produce them with a higher capacity.

Are there any other possible applications?

You could also use this material in super capacitors because it has a very high surface area, besides the fact that it is electrically conductive. Another idea - and we already have initial test results - is to fill the air with a polymer so we can achieve a polymer which is electrically conductive. This could remove static charges. So, it could be used in satellites, where you need both stiffness and electrical conductivity.

Interview: Zulfikar Abbany
Editor: Rob Mudge