Spatially resolved reaction environments in mechanochemical upcycling of polymers

Mechanochemical processing is an attractive and scalable approach for the upcycling of polymers. The complex and dynamic environment in ball milling, however, makes gaining insight into the physicochemical nature of the collisions driving mechanochemistry challenging, which, in turn, hampers the optimization of these processes. We used controlled single impacts followed by multiple spatially resolved analytical methods (focused ion beam microscopy, Raman spectro-microscopy, and small-angle X-ray scattering) and material point method simulations to gain unprecedented information about mechanochemical depolymerization of poly(ethylene terephthalate). These measurements highlight the contributions of plastic deformation, amorphization, and depolymerization during the transfer of kinetic energy in collisions relevant to ball mills and will enable reactor models based on fundamental kinetics.