Chemical Upcycling of Commodity Thermoset Polyurethane toward Multi‐functional Materials based on Oxime‐urethane Moiety

The massive accumulation of thermoset polyurethane foam (PUF) waste brings severe environmental challenges. Conventional recycling methods typically yield products with inferior performance and/or low economic value, while recent upcycling advances primarily focus on improving processability and mechanical performance, leaving functional enhancements largely unexplored. Here, we propose a chemical upcycling strategy that transforms PUF waste into multifunctional materials by leveraging oxime-mediated cleavage of its key bonds (urethane, urea, and biuret). This approach enables oximes to be readily embedded into commodity thermoset PUF, regenerating products with dynamic and photo-responsive oxime-urethane moieties. As a result, the upcycled products not only exhibit excellent mechanical properties but also demonstrate multiple advanced functionalities, including self-welding, shape reconfiguration, and spatially controlled fluorescent patterning. This work establishes an attractive pathway for functional upcycling of PUF waste.