As plastic: created of ultra-lightweight gold jewelry purity

Chemists have developed material that the content of the precious metal and the Shine is not inferior to the popular gold 750-th sample, but the easier it 5-10 times. The novelty will be useful in jewelry, chemistry and electronics.

Achievement is described in a scientific paper published in the journal Advanced Functional Materials group, headed Mezzenga Raffaele (Raffaele Mezzenga) of ETH Zurich.

Gold jewelry since ancient times, roads and prestigious. But this prestige is – literally-a heavy burden. The density of pure gold is 19 grams per cubic centimeter. That is a gold ball with a diameter of 4.6 cm weighs three pounds (!). Therefore, jewelers usually use an alloy of gold with a light copper.

One of the classic solutions is a gold 750-th sample, it is 18-Karat gold. It 75% precious metal (hence the 750), and everything else is copper. This composition has a density of 15 grams per cubic centimeter. The jewelry and accessories are still quite heavy.

to ease them even more, you need to reduce the gold content in the alloy. But the larger the proportion of copper, the less reason to believe the product is gold. Hardly wealthy lady will be pleased to phrase that in the society pages: “With exquisite copper jewellery, she shined like a brand new transformer.”

the Compromise between weight and purity of the metal have to find not only in jewelry but also in electronics, and in chemistry, where gold is used as a powerful catalyst.

Command Mezzenga approached the issue from the other side. What if I do not reduce the content of precious substances, and rather heavy to replace the copper with something more light?

In 2015, the research group has surprised the world by creating the “Golden foam” which does not sink in water. This aerogel is extremely lightweight due to the fact that most of it is accounted for by pores and air bubbles. However, the development did not satisfy the researchers.

“This material was too nettabstrong and did not respond to treatment. This time we have set ourselves a clear goal: to create a light gold, which also can be processed and used in most areas where there is gold,” says Mezzenga.

the skeleton of the new material is a latex based on polystyrene with addition of protein fibers. This “reference skeleton” embedded crystals of pure gold.

the Material is easy for two reasons. First, there are a lot of microscopic cavities filled with air. Second, the polymers are much lighter than copper.

the Photomicrograph of gold crystals, embedded in a polymer base.Illustration Stephan Handschin/ScopeM/ETH Zurich.

In the process of making the material passes aqueous solution, an aqueous gel, alcohol gel and aerogel. The density of the final product depends on the concentration of the initial solution. It can be changed by adjusting the substance for specific tasks.

For jewelry good option with a density of 1.7 grams per cubic centimeter. This material is almost vdevyatero usual lighter gold 750-th sample. Thus, with the same 75% precious metal, so it is still good for those who want to show the rich inner world of his purse. It is also important that the new gold is easy to process and preserves the characteristic luster.

Polymer-based micro-crystals and gold give the material unique properties.Illustration Stephan Handschin/ScopeM/ETH Zurich.

the Researchers have filed a patent application as the material and method of its manufacture. But they don’t intend to stop there.

for Example, the frame material can be made of polypropylene, which easily turns into liquid when heated. Chemists expect thus to effect PLa content view of gold at low temperatures.

“In General, our approach allows us to create almost any kind of gold at our discretion in accordance with desirable properties,” says Mezzenga.

By the way, earlier “News.Science” ( wrote about a two-dimensional gold, and the gold, which is harder than steel.

Text: To.Science