Now, Hyun Suk Wang and colleagues, from ETH Zurich, Switzerland, have demonstrated a light-triggered depolymerization technique that provides a path to better plastic recycling (Science 387, 874–880; 2025). The feat was carried out for PMMA (poly(methyl methacrylate)), a plastic commercialized as plexiglass. With the aid of light, the plexiglass (left image) is broken down into its monomer (right image) which can be used to make new, high-quality items.
According to the Wang and corresponding author Athina Anastasaki, their motivation was to depolymerize plexiglass to its starting material, the monomer, at temperatures much lower than those used for pyrolysis (a high-temperature (~500 °C) method to deconstruct polymers). They noted that in previous years the group has achieved low-temperature depolymerizations by making special, pre-designed polymers that contained reactive motifs, that is, exploiting engineered weaknesses to break down the plastic. But they noted that such ‘academic’ materials are not industrially produced and that they wanted to figure out how to depolymerize commercial materials.