ETH researchers have created an incredibly lightweight 18-carat gold, using a matrix of plastic in place of metallic alloy elements.
Lovers of gold watches and heavy jewellery will be thrilled. The objects of their desire may someday become much lighter, but without losing any of their glitter. Especially with watches, a small amount of weight can make all the difference. 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.
Formerly a postdoc in the ETH lab headed by Raffaele Mezzenga, Professor of Food and Soft Materials, Leonie van 't Hag 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, van 't Hag, Mezzenga and colleagues 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.
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