Chemical upcycling method offers vital plastic waste solution

Scientists at the University of Edinburgh, UK, and RPTU University Kaiserslautern-Landau, Germany, have developed a new chemical upcycling method that converts common plastics used in food packaging, 3D printing and biomedical implants into more eco-friendly materials that break down faster, offering a promising new route to tackle global plastic pollution1.

New method creates more degradable plastics

Researchers have devised a simple, one-step process to transform existing plastics into a more readily degradable material known as a polythionoester. This is achieved by altering the chemical structure of the original plastic: atoms of oxygen that are chemically bonded to carbon are removed and replaced with sulfur atoms.

A molecule known as a thionating agent is used to install sulfur in this way, enabling the rapid conversion of the starting plastic into a new sulfur-containing material with distinct physical properties and improved degradability.

Weaker bonds enable faster breakdown

The newly created polythionoesters are built from long molecules containing carbon-sulfur bonds. These bonds are much weaker than the carbon-oxygen bonds found in the original plastic, which gives the upcycled material different properties and makes it significantly easier to break down.

Researchers tested the method on polycaprolactone, an existing type of biodegradable polyester used in food packaging, 3D printing and biomedical implants. Although polycaprolactone is already considered biodegradable, the new approach offers a way to further enhance its degradability and tailor its properties.

Scalable process for plastic upcycling

The team reports that the thionation process is straightforward and easily scalable, suggesting it should be possible to convert large quantities of plastics quickly. They also note that the method can be adapted to upcycle other types of plastic, potentially broadening its impact across multiple sectors that rely on polymer materials.

Further research is required to fully understand the environmental impacts of the breakdown products of polythionoesters and to assess how these new materials behave in real-world conditions.

Addressing the global plastic pollution challenge

Around 99% of plastics currently in circulation are not biodegradable. Existing eco-friendly alternatives often degrade slowly or require high temperatures and harsh chemicals to break down. By offering a route to convert widely used plastics into materials that degrade more rapidly and under milder conditions, the new upcycling method could contribute to reducing plastic waste destined for landfill and the environment.

Dr Jennifer Garden, of the University of Edinburgh’s School of Chemistry, who co-led the study, said, “The thionation of polyesters is a challenging task, as these materials are less reactive towards thionation than many other polymers, and accessing polythionoesters via traditional routes can be difficult. What makes this discovery so exciting is that we’ve successfully developed a strategy that opens the door to a whole new range of sulfur-containing materials. We’re eager to see where this research takes us and are already looking forward to exploring the many possibilities that this breakthrough has to offer, paving the way for future studies in this promising field.”

The work was funded by UK Research and Innovation (UKRI), the Royal Society, the French National Research Agency and the French National Centre for Scientific Research (CNRS).

References

1. Hill M, Jeschke J, Mutlu H, Garden JA. Polyester metamorphosis via carbonyl-to-thiocarbonyl editing to tune polymer lifetime. Chem Circularity, May 21, 2026.

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