Introducing Dr. Lindsay Robinson
Chemical design-driven strategies to extend polymer network lifecycles
Commodity thermosets are generally landfilled or incinerated due to the presence of covalent crosslinks that are effectively irreversible due to their high bond dissociation energy. This poses a pressing environmental concern. An emerging class of thermoset alternatives is covalent adaptable networks (CANs), which are crosslinked by dynamic covalent bonds that can be cleaved and regenerated upon application of an external stimulus (such as heat or light). By taking advantage of the on-demand reversibility of these CAN crosslinks, the material can undergo more environmentally sustainable end-of-life fates, such as reprocessing, upcycling, and chemical recycling. The activation and efficiency of the stimuli-responsive crosslink exchange of many CANs are contingent on externally added catalysts, which are not covalently bound to the polymer network. Catalyst loss via pathways such as leaching and degradation transforms reversible crosslinks into (effectively) irreversible linkages.