Here's how the Swiss researchers create the new lightweight gold: first, they add the ingredients to water and create a dispersion. After adding salt to turn the dispersion into a gel, next they replace the water in it with alcohol.
Then they place the alcohol gel into a pressure chamber, where high pressures and a supercritical CO2 atmosphere enables miscibility of the alcohol and the CO2 gas; when the pressure is released, everything turns it into a homogeneous gossamer-like aerogel. Heat can be further applied afterwards to anneal the plastic polymers, thus transforming the material and compacting into the final desired shape, yet preserving the 18 carat composition.
If a piece of it falls onto a hard surface, it sounds like plastic. But it glimmers like metallic gold, and can be polished and worked into the desired form.
The researchers can even adjust the hardness of the material by changing the composition of the gold. They can also replace the latex in the matrix with other plastics, such as polypropylene. Since polypropylene liquifies at some specific temperature, "plastic gold" made with it can mimic the gold melting process, yet at much lower temperatures. Furthermore, the shape of the gold nanoparticle can change the material's colour: "nanoplatelets" produce gold's typical shimmer, while spherical nanoparticles of gold lend the material a violet hue.
As a general rule, our approach lets us create almost any kind of gold we choose, while the plastic gold will be in particular demand in the manufacture of watches and jewellery, it is also suitable for chemical catalysis, electronics applications or radiation shielding. The researchers have applied for patents for both the process and the material.
The researchers have applied for patents for both the process and the material.
