Scientists create foam made of gold

Scientists at the Swiss Federal Institute of Technology in Zürich (Eidgenössische Technische Hochschule Zürich or ETH) invented a new type of foam made of real gold. This aerogel consists of 98 parts air for every two parts solid material, making it light enough to keep it from sinking in a cappuccino.

"The so-called aerogel is a thousand times lighter than conventional gold alloys," said lead researcher Raffaele Mezzenga, professor of Food and Soft Materials at ETH. “It is lighter than water and almost as light as air.”

According to ETH Zürich, to produce the foam, the team heated milk proteins until they break down into minute fibres called amyloid fibrils. These are combined into a gold salt solution to form a gel-like fibrous mass that will be dried in a carbon dioxide bath.

The final product cannot be distinguished from the conventional form of gold. Plus, unlike solid gold, it can be shaped and bent by hand.

Gustav Nyström, first author of the study, stated that drying the delicate gold foam was challenging. Air drying could apparently damage the gold structure, hence they painstakingly dried it using carbon dioxide. The manufacturing process also allowed the researchers to manipulate the color and the gold’s absorption and reflection of light.

“The optical properties of gold depend strongly on the size and shape of the gold particles," Nyström claims. "Therefore we can even change the colour of the material. When we change the reaction conditions in order that the gold doesn't crystallise into microparticles but rather smaller nanoparticles, it results in a dark-red gold."

The team is optimistic that the new material could have many applications, possibly replacing the conventional form of gold in making watches and other jewellery. They are also hopeful that this could be of use in the field of chemistry and physics.

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