A new way to get airbrushed 03.05.2015

When we talk about something light and weightless, we often use the adjective "air". However, air still has mass, albeit small - one cubic meter of air weighs a little over a kilogram. Is it possible to create a solid material that would occupy, for example, a cubic meter, but at the same time would weigh less than a kilogram? This problem was solved at the beginning of the last century by the American chemist and engineer Stephen Kistler, who is known as the inventor of the airgel.

The 3D-printed macrostructure of the airbrush gives it unique mechanical properties without losing its "graphene" nature. Credit: Ryan Chen/LLNLThe 3D printed macrostructure of airbrushed airbrush gives it unique mechanical properties without losing its "graphene" nature.

Probably, for many, the first association with the word "gel" is associated with some kind of cosmetic product or household chemicals. Although, in fact, a gel is a completely chemical term that refers to a system consisting of a three-dimensional network of macromolecules, a kind of framework, in the voids of which there is a liquid. Due to this molecular framework, the same shower gel does not spread over the palm of your hand, but takes on a tangible form. But it is impossible to call such an ordinary gel airy - the liquid, which makes up most of it, is almost a thousand times heavier than air. This is where the experimenters came up with the idea of ​​how to make an ultra-light material.

If you take a liquid gel, and in some way remove water from it, replacing it with air, then as a result, only a skeleton will remain of the gel, which will provide hardness, but at the same time have practically no weight. This material is called airgel. Since its invention in 1930, a kind of competition has begun among chemists to create the lightest airgel. For a long time, a material based on silicon dioxide was mainly used to obtain it. The density of such silicon aerogels ranged from tenths to hundredths of a gram per cubic centimeter. When carbon nanotubes began to be used as a material, the density of airgels was reduced by almost two orders of magnitude. For example, airgraphite had a density of 0,18 mg/cm3. To date, the palm of the lightest solid material belongs to airbrush, its density is only 0,16 mg / cm3. For clarity, a meter cube made of airbrushed paper would weigh 160 g, which is eight times lighter than air.

However, chemists are driven by far not only sports interest, and graphene as a material for airgels began to be used not by chance. Graphene itself has a lot of unique properties, which are largely due to its flat structure. On the other hand, aerogels also have special characteristics, one of which is a huge specific surface area, which amounts to hundreds and thousands of square meters per gram of substance. Such a huge area arises due to the high porosity of the material. Chemists have already succeeded in combining the specific properties of graphene with the unique structure of airgels, but researchers from the Livermore National Laboratory for some reason also needed a 3D printer to create airbrush.

In order to print airgel, first it was necessary to create a special ink based on graphene oxide. In addition to the fact that they should be airbrushed, it is necessary that such ink be suitable for 3D printing. Having solved this problem, chemists got their hands on a method by which it is possible to produce airbrush with the desired microarchitecture. This is very important, because in addition to the properties inherent in graphene, such a material will also have interesting physical properties. For example, the sample that the authors of the study received turned out to be surprisingly elastic - an airbrushed cube could be compressed ten times without harm to the material, while it did not lose its properties during repeated compression-stretching.

The ability to repeatedly compress distinguishes the printed airbrush from the one obtained by the "usual" way. One of the practical applications of the new airbrush could be flexible electric batteries, where the large inner surface of the material would be used as an electrode, while the printed structure would give it the desired flexibility.