Photo-initiated solvent-mediated depolymerization of consumer poly(methyl methacrylate) without chlorinated reagents.

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Conventional chemical recycling of polymethyl methacrylate (PMMA) requires high temperatures (350-400°C).
• Developing energy-efficient and scalable depolymerization methods is crucial for plastic waste management.

Purpose of the Study:

• To establish a low-temperature chemical recycling process for PMMA.
• To achieve high monomer yields from consumer plastic waste through efficient depolymerization.

Main Methods:

• UV illumination under oxygen-free conditions at temperatures between 120-180°C.
• Utilizing various solvents, including aromatic and non-chlorinated options, to optimize depolymerization.
• Investigating the role of chlorine radicals in the depolymerization process.

Main Results:

• Achieved gram-scale degradation of PMMA with >95% conversion and >70% monomer yield.
• Demonstrated efficient depolymerization at high concentrations (>1 M) in specific aromatic solvents.
• Showed that chlorine radicals are not essential but can lead to functionalized byproducts.

Conclusions:

• A scalable, low-temperature UV-assisted chemical recycling method for PMMA has been developed.
• The process offers a viable route for upcycling PMMA waste into valuable monomers.
• This advancement provides new pathways for enhancing plastic circularity and sustainability.