Researchers at the University of Bath have developed a breakthrough method for recycling one of the world’s most widely used plastics - Perspex/Plexiglass which is made from the transparent thermoplastic polymethyl methacrylate (PMMA) - using a low temperature, light activated process that avoids the need for chlorine based chemistry.

The work, led by Bath Institute of Sustainability and Climate Change (ISCC) core members Dr Jon Husband and Dr Simon Freakley and co-authored by the Innovation Centre for Applied Sustainable Technologies (iCAST) Director Professor Matthew Davidson as part of iCAST, has just been published in Nature Communications.

The Perspex problem

Perspex is used at approximately 3 million tonnes per year and has applications across sectors ranging from automotive components and construction materials to screens and protective barriers.

Mechanical recycling is the typical method for plastic recycling, which simply melts and reforms plastics for new uses. This leads to discolouration and quality decline and therefore is poorly suited for Perspex due to its use in glass-like applications.

Recent industry focus has been on pyrolysis – or the heating of Perspex to 350-400°C - to turn the plastic back into its monomer building blocks to be made from scratch again, in pristine quality. The downsides of this technique are that it is very energy intensive and has poor tolerance to contamination due to its chemically unspecific nature.

A cleaner, safer way to “unzip” acrylic plastics

Jon Husband, ISCC Research Fellow says:

With current methods for recycling both energy intensive and inefficient, the demand for cleaner, more efficient recycling technologies has never been greater.

“Plastic recycling can be tough to make economically feasible, due to issues around high energy costs and low quality product; issues this work directly addresses.”

The Bath team’s discovered process uses UV illumination under oxygen free conditions to chemically specifically break down real consumer-grade PMMA plastic into its original monomer building blocks. Crucially, the chemistry works at only 120-180°C, far below the 350-400°C typically needed for conventional pyrolysis-based recycling.

This temperature reduction significantly lowers the energy input required for chemical recycling, potentially improving both environmental performance and commercial scalability.

High yields suitable for true circularity

Dr Simon Freakley says: “Developing new chemical recycling approaches matters because it turns waste back into a pristine new material, rather than a lower‑grade low-value material destined for eventual disposal.”

The new approach delivers over 95% conversion of the plastic and yields more than 70% monomer, which can then be purified and repolymerised into “as new” materials. This ability to recover high quality monomers from real, consumer used PMMA demonstrates the method’s potential to support a fully circular lifecycle for acrylic plastics, rather than downcycling or incineration.

Scalable, sustainable plastics recycling

The Bath team’s discovery advances beyond a concurrent discovery in PMMA recycling from researchers at ETH Zurich which relies on UV‑activated chlorinated solvents to drive depolymerisation. What sets the Bath researcher’s discovery apart is that the depolymerisation proceeds without requiring chlorine radicals, meaning the method is compatible with more sustainable solvents. These greener solvent options support safer industrial operation and reduce the environmental impact associated with handling chlorinated chemicals.

This new light driven, chlorine free depolymerisation method developed at the University of Bath represents a meaningful step toward truly scalable and sustainable plastics recycling. By cutting energy use, allowing safer and more sustainable solvents, and recovering high‑purity monomers from real consumer plastics, this approach offers a clear pathway toward genuine circularity in acrylic materials.

That this transformative chemistry does not require chlorine at all opens the door to greener, simpler and more industrially viable recycling routes. With global PMMA production now approaching four million tonnes each year, the need for next generation, low impact chemical recycling technologies has never been more urgent.