This plastic gold is as pure as your original gold
Gold is the most-loved metal around the world. As nice as it looks in a watch or ring, pure gold would get too heavy for everyday wear, so it’s often lightened up with alloys. Now, by mixing it with plastic instead of other metals, researchers at ETH Zurich have created a new form of gold with as little as one-10th the usual weight, but retaining the same purity.
The traditional 18-carat gold typically comprises 75 percent gold and 25 percent copper. While 24-karat gold is entirely pure, that’s not entirely practical for jewelry. To make the precious metal lighter and more resistant to damage, it’s mixed with another metal, often copper, giving it a purity of 18 karats.
How is it done?
The researchers began by mixing gold nanocrystals with protein fibers, polymer latex, water, and salt to create a gel. They then replaced the water with alcohol and placed the gel inside a high-pressure carbon dioxide (CO2) chamber. The reaction between the gas and alcohol transformed the golden plastic into a light aerogel that could be heated to melt and mold into whatever form was needed.
Along with being much lighter, the new type of gold has several other advantages over traditional forms. Properties like hardness can be easily tweaked at the beginning of the process by changing the composition. Even the color can be changed by swapping in different shaped nanoparticles, with spheres giving the material a violet hue.
Not just for beautiful ornaments, gold is used in window glass and astronaut helmets to reflect infrared rays while allowing sunlight to pass through, and at the same time keeping it cool.