Researchers create lightweight 18-carat gold made of plastic
London, Jan 12 (IANS) A good news for jewellery lovers. The objects of their desire may someday become much lighter, but without losing any of their glitter – especially with gold watches, as researchers have created an incredibly lightweight 18-carat gold, using a matrix of plastic in place of metallic alloy elements.
According to the study, the research team from the Swiss university ETH Zurich have developed 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, the study said.
Study researchers Leonie van’t Hag, Raffaele Mezzenga and team 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, said the study, published in the Advanced Functional Material.
According to the researchers, gold platelets and plastic melt into a material that can be easily processed mechanically.
For the finding, the research team first added the ingredients to water and created a dispersion. After adding salt to turn the dispersion into a gel, they next replaced the water in it with alcohol.
Thereafter, they placed the alcohol gel into a pressure chamber, where high pressures and a supercritical CO2 atmosphere enables miscibility of the alcohol and the CO2 gas; when the pressure is released, everything turns it into a homogeneous gossamer-like aerogel.
Heat can be further applied afterwards to anneal the plastic polymers, thus transforming the material and compacting into the final desired shape, yet preserving the 18-carat composition, the researchers said.
According to the study, this gold has the material properties of a plastic. If a piece of it falls onto a hard surface, it sounds like plastic.
It, however, 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.
The researchers noted that, while 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.
