Scientists have discovered a way to convert widely used plastics into new materials with distinct properties that degrade more rapidly. Applying this new process to upcycle existing plastics—such as those used for food packaging and in 3D printing—could contribute to tackling global plastic pollution issues, researchers say.
This is an important advance as some 99% of plastics in circulation are not biodegradable, and the eco-friendly alternatives that do exist often break down slowly or require high temperatures and harsh chemicals, the team says.
Researchers at the University of Edinburgh and RPTU University Kaiserslautern-Landau, Germany, have led the development of a new method of producing a type of plastic—known as a polythionoester—that is more readily degradable. Their research paper is published in the journal Chem Circularity.
The biodegradable material is produced by altering the chemical structure of an existing plastic, removing some atoms of oxygen chemically bonded to carbon and replacing them with sulfur atoms. A molecule capable of installing sulfur in this way—known as a thionating agent—is applied in a simple one-step process to achieve this transformation.
Long polythionoester molecules are built from carbon-sulfur bonds that are much weaker than the carbon-oxygen ones in the original plastic, unlocking different physical properties while also making them significantly easier to break down, the team reports.
Researchers trialed the new method on an existing type of biodegradable plastic—polycaprolactone—that is used in areas including food packaging, 3D printing and biomedical implants.
The straightforward process is easily scalable, meaning it should be possible to convert large quantities of plastics rapidly, the team says. The process can also be adapted to upcycle other types of plastic, further expanding its possible applications, they add.
Further research is needed to fully understand the possible environmental impacts of the breakdown products of polythionoesters.
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. Collaborating with this team has been an absolute joy—their enthusiasm, motivation, and expertise have made every step of this journey a pleasure, and I feel fortunate to work alongside such a talented group of scientists."