Scientists at the University of Surrey have developed a new type of plastic that turns into a gas when heated and reforms into a solid when cooled, opening up a new approach to polymer processing and recycling.
The research, published in Macromolecules, introduces a polymer that could make certain materials easier to apply, remove and recycle by avoiding some of the complex processing steps used in conventional plastics recycling.
Many everyday plastics, including polyethylene used in carrier bags, food packaging and shampoo bottles, are highly persistent and are not suitable for chemical recycling. Other chemically recyclable polymers have been developed, but they often require temperatures of around 150C to 200C to break down, and the recovered material may need further chemical processing before it can be reused.
Polymer turns into vapour at 90C
The University of Surrey team’s material is similar to polyethylene in that it is soft, insoluble and hydrophobic. However, when heated to around 90C, it undergoes efficient depolymerisation, breaking down into its individual building blocks, known as monomers.
Unlike most depolymerisation processes, where recovered monomers are liquids, the new material forms a gas. As the vapour cools, it spontaneously reforms into the original waterproof polymer with the same properties as before.
“Most plastics are designed to be stable, which is exactly what makes them difficult to recycle or remove. We’ve shown that it’s possible to create a material that behaves very differently – one that can transform into a vapour at relatively low temperatures before naturally rebuilding itself into the same polymer,” said Dr Peter Roth, Senior Lecturer in Applied Organic and Polymer Chemistry at the University of Surrey and corresponding author of the study.
“This isn’t a replacement for conventional plastics, and it’s certainly not a solution to the global plastic waste problem. But it does introduce a new concept that could inspire an entirely new generation of circular materials.”
Potential uses in recyclable coatings
To demonstrate the concept, the researchers tested three possible applications.
First, they created waterproof polymer coatings by allowing the polymer vapour to condense onto a surface. They then showed that these coatings could be removed simply by reheating them, causing the polymer to evaporate.
The team also demonstrated that a contaminated polymer could be purified through sublimation, separating the polymer from a model additive before it reformed as a clean solid.
The proof-of-concept work could eventually support new ways of applying and removing waterproof coatings, particularly in settings where liquid coatings struggle to cover complex surfaces.
“The exciting part is that we’ve demonstrated a principle that wasn’t previously available. If we can learn how to tailor this chemistry, it could eventually lead to new materials that are easier to apply, remove and recycle than many of today’s plastics,” said Touseef Kazmi, postgraduate researcher at the University of Surrey and lead author of the study.
A new route for circular materials
The discovery adds to wider research into degradable polymers and recyclable material systems, as scientists look for new ways to reduce waste and improve the circularity of plastics.
While the researchers stress that the material is not designed to replace mainstream plastics, its reversible solid-to-gas behaviour could provide a platform for future materials that are easier to recover, purify and reuse.
FAQs
What has the University of Surrey developed?
Researchers have developed a new polymer that turns into a gas when heated to around 90C and reforms into the same solid material when cooled.
Why is this important for recycling?
The material could simplify certain recycling and removal processes because it breaks down into gaseous monomers and then reforms without needing complex additional chemical processing.
Is this new polymer a replacement for conventional plastics?
No. The researchers say it is a proof of concept rather than a direct replacement for conventional plastics or a complete solution to plastic waste.
Where could the material be used?
Potential applications include recyclable waterproof coatings, removable coatings and purification processes for contaminated polymer materials.
Where was the study published?
The research was published in Macromolecules, a peer-reviewed journal from the American Chemical Society.
