We present a cesium carbonate-mediated method to upcycle poly(propylene carbonate) (PPC) waste into beta-hydroxy sulfides, selenides, and phenoxides via selective thermal depolymerization. The process tolerates diverse nucleophiles, including those from multilayer plastics. Mechanistic studies support a cesium aryl thiolate-driven nucleophilic degradation. The beta-hydroxy products are easily functionalized, and the base is recyclable, offering a sustainable route for PPC valorization.

Foreign