18-Carat Gold Made From Plastic

in #science5 years ago

Take nano-particles of gold, mix them with an appropriate polymer, add salt, alcohol then put the mixture into a pressure chamber. What you get is light gold that looks like gold, glistens like gold, works like gold in chemical and physical processes but it five to ten times lighter than normal gold.

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Image by Steve Bidmead from Pixabay

Gold Is Heavy

Gold is an interesting material. It glistens seductively, chemically it is very durable and because of its density, it is very heavy. If any of you ever got to hold a golden brick you know what I am talking about. But for some of those who like golden jewelry or things like golden watches – this may be a problem. The high density – 19.3 grams per cubic centimeter can make even small golden things heavy. But a newly developed material from ETH Zurich could now change that.

Leonie van 't Hag and her coworkers created the amazing 18-carat gold that is based on a plastic matrix. Such gold is incredibly light yet it retains its beautiful glisten. The newly made gold is about five to ten times lighter compared to traditional 18-carat gold. In fact, 18-carat gold is made from three-quarters gold and one-quarter copper.

Lighter 18-Carat Gold

The density of the “new” gold is just 1.7 grams per cubic centimeter. Yet it is still 18-carat gold. How is that even possible? The key was to use protein fibers and polymer latex that creates a matrix into which the scientists put nanoplates of gold. Another thing that contributes to the low weight is the fact that the new material includes a high number of tiny air bubbles.

Van 't Hag and her colleagues first mixed all the ingredients with matter and created a dispersion. When they then added salt the dispersion turned into a gel in which they then chemically replaced water with alcohol. Such a gel was then placed into a pressure chamber where the high pressure and an atmosphere with carbon dioxide created a homogeneous web-like aerogel. This aerogel then transformed into the final material thanks to high temperature. After all this, the material kept its 18-carat gold composition.

Interestingly, the new “plastic gold” has a number of attributes normally associated with plastic, not gold. When you drop it to a hard surface it sounds like plastic falling. But it also glistens like regular gold and can be molded as you need. Plus, the scientists developed a process in which they increase the hardness of this intriguing material by changing the nanoparticles used.

They could also use a different polymer instead of the latex, like polypropylene. And as a bonus, polypropylene liquefies at a specific temperature so the “light gold” can be smelted down just like regular gold just at a much lower temperature than regular gold. And by changing the shape of the nanoparticles they were able to change the color of the final “light gold”. For example, when they used ball-shaped particles of gold instead of the nanoplates the “light gold” got a purple hue.

Van 't Hag and her team are convinced that their light gold could find use in jewelry, watches and similar accessories. It could also be useful for chemical analysis, electronics but even for radiation shielding technologies.

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