Light triggering processes break down polymers into monomers and make recycling easier
The return of commercially available plexiglass to the starting material, the monomers. Credits: Hyun Suk Wang and Athina Anastasaki
A team of materials scientists and engineers from Eth Zurich have developed a light chemical process to break down specific polymers into component monomers. This paper has been published in Journal Science.
In recent years, scientists have noticed new problems associated with the mass production of polymers. Something prominent can be found in every part of the world, including almost everyone on the planet. Part of the problem is the difficulties and costs associated with recycling plastics, making it easier to throw them into the garbage and into the ocean.
In this new study, Swiss researchers developed a method to break down plastics into monomeric components, allowing for much easier and cheaper recycling.
Plastics are polymers, substances made up of large molecules called polymers, and are made up of smaller subunits called monomers. They are formed using a process called polymerization. This essentially binds the monomer to a single material, namely plastic. Pulling them apart again has proven difficult and expensive up to now.
In a new process, the polymer is placed in a dichlorobenzene solvent and then the violet light shines as the reaction occurs in the solvent. No reagents or other catalysts are required. The only other warning is that the conditions for VAT must be kept above 90°C and the light must remain forever. Once finished, the result is a VAT filled with monomers and other chemicals that can be easily separated and recycled.
This technique was discovered by chance, so the team tried to explain why it worked. They discovered that dichlorobenzene produces chlorine radicals under light when exposed to polymers. The radical then tugs hydrogen atoms from a seemingly random part of the polymer backbone and breaks. Better yet, when it broke, a new radical formed and kicked out more reactions.
Researchers acknowledge that the response is slow, but also note that it is high yield, simple, simple and inexpensive. They suggest that recycling of plastics around the world can be altered.
Details: Hyun Suk Wang et al, visible photoinduced polymethacrylate depolymerization, Science (2025). doi:10.1126/science.adr1637
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Quote: The light attracted process decomposes polymers into monomers and retrieves from February 22, 2025 from https://phys.org/news/2025-02-Trigged Polymers – Agear Reschückling To make it easier (February 22, 2025)
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