Plastic is a globally important product; its versatility means you’ll find it in everything from electronics to furniture, prosthetic limbs to vehicles. There’s no doubt that it plays a big part in society. But on the flip side—it’s an environmental disaster. Because it degrades slowly, it accumulates in landfills for hundreds of years and can gradually leach harmful chemicals that make their way into groundwater. It also builds up in our oceans and can harm or kill marine animals. Furthermore, burning or melting it can release toxic emissions into the air.
There is therefore a need for plastics that don’t linger in the environment, which is what scientists from North Dakota State University have been working towards developing. Now, they’ve managed to come up with a plastic that breaks down upon exposure to light, and remarkably, it takes just three hours to fully degrade.
To fabricate their new material, they concocted a solution of molecules derived from fructose, a simple sugar found in foods such as fruit, and light-absorbing molecules called phototriggers. By heating this mixture, the scientists were able to create long, repeating chains of small molecules that formed a solid plastic when cooled.
Next, they exposed the plastic to UV light at a wavelength of 350 nanometers, which is within the range of wavelengths that the sun emits. This caused the light-absorbing molecules to break off from the chains of molecules, which triggered the plastic to start to degrade. The process was so efficient that in this proof-of-concept experiment, it took just three hours of exposure to UV light for the plastic to break down into a clear solution, indicating that the plastic had been reduced to its soluble building-block molecules.
According to the team’s recently published paper in Angewandte Chemie, these molecules can then be recovered and re-used to make new plastic, which helps reduce the demand for raw materials.
Obviously, we don’t want our garden furniture to start melting as soon as it's outside, so this plastic isn’t practical for many applications. However, it would be very useful in electronic gadgets that are notoriously difficult to recycle and are continuing to cause serious waste problems.
The researchers are hopeful that with further development, their plastic can eventually be commercialized, but first they need to work out whether the phototriggers influence certain properties of the plastic, such as durability.
[Via Science, Angewandte Chemie]
