Scientists Use Plastic To Create Lightweight 18-Carat Gold


CCSS NAS-2 360 Words 3-Minute Listen
The new plastic gold closely resembles its metallic gold but it's much lighter (Credit: ETH Zurich/Peter Rüegg)

While jewelry crafted from gold can be gorgeous, even ardent fans will admit that wearing the heavy metal over long periods of time can get a little cumbersome and annoying. Now, researchers from Swiss university ETH Zurich have created a new form of lightweight gold that weighs five to ten times less than traditional 18-carat gold — which typically comprises 75 percent gold and 25 percent copper — but retains the same purity.

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. "This gold has the material properties of a plastic," says team leader Raffaele Mezzenga, professor of Food and Soft Materials at ETH Zurich.

A microscope image of gold nanoplatelets embedded in a latex matrix (Credit: Stephan Handschin/ScopeM/ETH Zurich)

In addition to being lighter, the "plastic" gold has other advantages over traditional forms. It can be melted into shape at about 105 degrees Celsius (221 degrees Fahrenheit), much lower than the 1,064 degrees Celsius (1,947 degrees Fahrenheit) required to melt pure 24-carat gold. The metal's firmness can be easily tweaked by changing the composition at the beginning of the process. It is also possible to vary the color by swapping the shape of the gold nanoparticles inside the matrix. For example, irregularly-shaped nanoplatelets will produce the conventional yellow shimmer, while spherical nanoparticles will result in gold with a violet hue. "As a general rule, our approach lets us create almost any kind of gold we choose, in line with the desired properties," says Mezzenga.

The researchers, who published their study in the journal Advanced Functional Materials on January 10, 2020, believe the new lightweight gold will be able to replace the metallic version in most traditional applications, including jewelry and watches. However, given that most buyers associate high-quality gold with weight, that may take some time. But the gleaming material will undoubtedly be beneficial for use inside electronic devices, chemical catalysts, and even radiation shielding.


Get the Workbook for this article!

Workbook contains: Article, Reading Comprehension, Critical Thinking Questions, Vocabulary in Context (+ answers), Multiple Choice Quiz (+ answers), Parts of Speech Quiz (+ answers), Vocabulary Game (+ answers)
Cite Article
  • bluedemon
    bluedemonMonday, December 7, 2020 at 5:39 pm
    So cool!!
    • jkbear
      jkbearMonday, November 16, 2020 at 2:20 pm
      That is so cool. I could become rich with that!
      • ellie0307
        ellie0307Sunday, August 16, 2020 at 4:37 am
        Very interesting
        • l78
          l78Wednesday, May 27, 2020 at 10:25 am
          18 Karat gold! That's a lot of money! 💰
          • polly254
            polly254Thursday, April 30, 2020 at 9:04 am
            Once I watched a show where someone said that 18 carot gold was worthless
            • queenscience12
              queenscience12Wednesday, April 22, 2020 at 9:51 am
              It kind of looks like a chocolate coin
              • deadster
                deadsterWednesday, April 15, 2020 at 1:32 pm
                The mix of the chemicals in the container mixed with carbon dioxide, this is incredible, I must try this for myself!
                • apex_games297
                  apex_games297Sunday, April 19, 2020 at 6:23 am
                  I don't think so because the article says that it also needs a pressure carbon dioxide chamber.
                • hhay20485792
                  hhay20485792Thursday, March 26, 2020 at 8:08 am
                  all he did was drop it??
                  • fudge05
                    fudge05Thursday, March 26, 2020 at 7:54 am
                    It sounds easy but also kind of difficult
                    • dantdmroblox
                      dantdmrobloxSaturday, March 21, 2020 at 8:46 am
                      Does it mean you can microwave plastic to make gold???
                      • fudge05
                        fudge05Thursday, March 26, 2020 at 7:55 am
                        No that is not even remotely close to what that means.