ETH researchers have created an incredibly lightweight 18-carat gold, using a matrix of plastic in place of metallic alloy elements.
No one wants to wear a heavy watch on their wrist, even if it’s made of real gold. After a time, it becomes uncomfortable and annoying.
This new invention will help the Gold Watch lovers to get lighter watches without losing their glitters.
Previous research set to create a new form of gold that weighs about five to ten times less than traditional 18-carat gold. The conventional mixture is usually three-quarters gold and one-quarter copper, with a density of about 15 g/cm3.
That’s not true for this new lightweight gold: its density is just 1.7 g/cm3. And nonetheless it is still 18-carat gold. How was this miraculous lightness achieved? Instead of a metal alloy element, the researchers used protein fibres and a polymer latex to form a matrix in which they embedded thin discs of gold nanocrystals. In addition, the lightweight gold contains countless tiny air pockets invisible to the eye. The researchers’ study on this process has just been published in the journal Advanced Functional Materials.
This gold has the material properties of a plastic. 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.
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.
News Source: ETH Zurich
