Using this new process to upcycle existing plastics, such as those used in food packaging and 3D printing, could help address global plastic pollution.
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This is a significant step forward because about 99 percent of plastics in use are not biodegradable. Even the eco-friendly options available usually break down slowly or require high heat and strong chemicals, say researchers at the University of Edinburgh and RPTU University Kaiserslautern-Landau, Germany.
Degradable plastic
Researchers have led the development of a new method of producing a type of plastic – known as a polythionoester – that is more readily degradable.
According to Dr Jennifer Garden, School of Chemistry,” 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.”
To make the biodegradable material, scientists change the chemical structure of an existing plastic. They remove some oxygen atoms that are bonded to carbon and replace them with sulfur atoms.
A molecule that can add sulfur in this way, called a thionating agent, is used in a simple one-step process to make this change.
Long polythionoester molecules contain carbon-sulfur bonds, which are much weaker than the carbon-oxygen bonds found in the original plastic. This change gives the material new physical properties and makes it much easier to break down, the team reports.
Waste solution
Researchers trialled 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 team says their simple process can be scaled up, so it should be possible to convert large amounts of plastic quickly. They also note that the method could be adapted to upcycle other types of plastic, making it even more useful.
However, further research is needed to fully understand the possible environmental impacts of the breakdown products of polythionoesters.
The findings are reported in the journal Chem Circularity, a new sustainability focussed publication within the Cell Press portfolio. The research 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).
