Polyurethane with β‐Selenocarbonyl Structure Enabling the Combination of Plastic Degradation and Waste Upcycling

Abstract Degradable polymers offer a promising solution to mitigate global plastic pollution, but the degraded products often suffer from diminished value. Upcycling is a more sustainable approach to upgrade polymer waste into value‐added products. Herein, we report a β‐selenocarbonyl‐containing polyurethane (SePU), which can be directly degraded under mild conditions into valuable selenium fertilizers for selenium‐rich vegetable cultivation globally, enabling both plastic degradation and waste upcycling. Under oxidation condition, this polymer can be easily and selectively degraded via selenoxide elimination reaction from mixed plastic waste. The degraded product can serve as effective selenium fertilizers to increase selenium content in radish and pak choi. The SePU exhibits excellent mechanical properties. Additionally, we observed the formation of spherulites‐like selenium particles within the materials during degradation for the first time. Our research offers a successful application of selenoxide elimination reaction in the field of plastic degradation for the first time, endowing plastics with both degradability and high reusable value. This strategy provides a promising solution to reduce pollution and improve economy and sustainability of plastics.