A new approach for breaking plastic waste down to monomers

Researchers have reported a method for breaking down commercial polymers like Plexiglass into monomers, a form more desirable for reuse. This could help alleviate the growing plastic waste stream. Most current plastic recycling methods rely on macroscopic mechanical shredding, cleaning and reprocessing. As a result, the properties degrade relative to the virgin polymer. Chemical decomposition to the original monomer would enable more thorough purification and then repolymerization to restore ideal performance. Here, Hyun Suk Wang and colleagues report the discovery that in dichlorobenzene solvent, violet light irradiation can cleanly break down polymethacrylates such as Plexiglass to their original monomers. The process appears to involve hydrogen abstraction from the backbone by small quantities of chlorine radicals liberated from the solvent. “The possibility to perform multigram-scale depolymerizations and confer temporal control renders this methodology a versatile and general route to recycling,” say the authors.