Mapping pore-level activity of catalysts for polymer upcycling through dielectric spectroscopy*

Polymer upcycling by catalytic scission provides a powerful route to convert waste plastic to valuable chemicals. Despite the discovery of many promising catalytic reaction schemes that cleave polyolefins to form selective products, reaction engineering of upcycling processes is hindered by a lack of understanding of pore-level macromolecular deconstruction. Change in segmental dynamics can serve as a marker for the progress of chain scission in upcycling reactions. In this talk, we present a method to monitor the progress of a scission-based reaction inside porous catalysts by tracking the evolving dielectric signature of the reacting polymer. Nanoporous membranes of anodic aluminum oxide are filled with poly(n-butyl) methacrylate as a model for polymer-filled catalytic pores. Change in the measured dielectric properties upon thermal depolymerization is correlated to the rate of scission of polymeric species. To highlight the applicability of this technique to catalytic upcycling of commercial polyolefins, the scission of poly(ethylene-alt-propylene) is tracked inside functionalized nanopores. Nanorheological characterization of pore-level catalytic activity will help guide the design of catalyst morphology for efficient upcycling reactions.