Chemical Upcycling of Commodity Thermoset Polyurethane toward Multi-functional Materials based on Oxime-urethane...

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.