Ina Vollmer (UU)

Improving current recycling technology could help increase the low plastic recycling rate of 12%. The aim of depolymerization is to produce monomers to make high-quality plastics again. However, the state-of-the-art for polypropylene (PP) and polyethylene is pyrolysis, which produces low-value product mixtures, due to the high temperature applied, which is required for thermal C–C bond cleavage.

The team of Vollmer investigates polymer conversion in a mechano-chemical ball mill reactor, enabling conversion below 60 °C instead of more than 500 °C used in pyrolysis. Instead of heat, mechanical forces drive C-C scission. A novel catalyst was developed, catalytically functionalizing the surface of ZrO2 grinding spheres. Density functional theory and in-situ electron spin resonance spectroscopy suggests that the polymer radicals interact with Zr3+ on the spheres. Radical kinetics were determined and modelled using radical scavengers and vibrational spectroscopy.

The technology is currently being upscaled with the startup Repolyze, founded in 2026.