What if, instead of waiting a million years and spending a million dollars to mine diamonds, you could turn plastic into diamonds in the blink of an eye using lasers? Too far-fetched? Actually, that’s the world you now live in.

By shooting a high-performance laser at a thin sheet of polyethylene terephthalate (PET) plastic, common in food and beverage containers, German scientists have shown that the foil-like material will briefly heat up to 6,000 degrees Celsius and generate a shock wave.

This shock wave compresses the matter to millions of times the atmospheric pressure for a few billionths of a second and the extreme pressure forges tiny ‘nanodiamonds’, the team revealed in a research paper published in Science Advances journal last month.

“So far, diamonds of this kind have mainly been produced by detonating explosives,” study co-author Professor Dominik Kraus of the University of Rostock said. “With the help of laser flashes, they could be manufactured much more cleanly in the future.”

After a laser fires 10 flashes per second at plastic film, nanodiamonds shoot out of the film and land in a collecting tank filled with water. There they decelerate, allowing researchers to filter and effectively harvest them.

It’s a process that is believed to occur naturally on giant ice planets. Temperatures on Neptune and Uranus, for example, reach several thousand degrees Celsius and their atmospheric pressure is millions of times greater than on Earth.

“The effect of the oxygen was to accelerate the splitting of the carbon and hydrogen and thus encourage the formation of nanodiamonds,” the study authors wrote. “It meant the carbon atoms could combine more easily and form diamonds.”

The scientists landed on everyday PET, the resin out of which plastic bottles are made, as it has “a good balance between carbon, hydrogen and oxygen to simulate the activity in ice planets”.

The breakthrough could help lead to more demand for water bottles and other containers that often end up in the sea, the team said, suggesting a related boon for the environment.

For resources investors, the achievement is impressive and the applications useful (such as in the construction of quantum sensors), but with the nanodiamonds being incredibly small, it’s not likely to revolutionise the mining industry any time soon.

Sources:

• science.org, Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction
• unirostock.de, Making nanodiamonds out of bottle plastic