Circular plastics technologies: depolymerization of polymers into parent monomers

Abstract

While most commodity plastics were not designed to easily depolymerize, some common plastics can be broken down into their parent monomers in the presence of heat, pressure, catalysts, and/or solvent. Here, we provide a high-level overview of the depolymerization technologies that have been studied and/or scaled as promising monomer-loop recycling processes for selective plastic waste streams. Namely, commodity plastics that are considered unzippable/depolymerizable include polyethylene terephthalate, polyamides, polymethyl methacrylate, and polystyrene. Monomer-loop recycling technologies are one of several pathways toward a circular economy for plastics.