Ir(triNHC)-catalyzed upcycling of waste poly(butylene terephthalate) into biodegradable plastic

Despite the recognition of everyday produced, consumed, and disposed plastics as potentially sustainable chemical resources, the development of efficient catalytic approaches to transform them into industrially valuable chemicals, particularly biodegradable polymer feedstocks, remains a significant challenge. Addressing this limitation, we report an innovative Ir(tri- N -heterocyclic carbene [triNHC])-catalyzed upcycling strategy that enables the highly efficient and selective conversion of waste poly(butylene terephthalate) (PBT) into γ-hydroxybutyric acid (GHB) and succinic acid (SA). GHB and SA, derived directly from PBT, are subsequently polymerized to yield biodegradable poly(4-hydroxybutyrate) (P4HB) and poly(butylene succinate-co-terephthalate) (PBST), respectively. This approach offers an efficient pathway for the chemical upcycling of a common plastic waste stream into industrially relevant and environmentally benign biodegradable polymers, thereby contributing to a circular economy for plastics. • Ir(triNHC)-catalyzed conversion of PBT into γ-hydroxybutyric acid and succinic acid • From waste plastic (PBT) to biodegradable plastics (P4HB and PBST) • Ir(triNHC)-catalyzed open-loop upcycling of waste PBT Lee et al. effectively upcycle diverse waste PBT plastics, including colorless, colored, and impure materials, into high-value GHB and SA using an Ir(triNHC)-catalyzed process. These products serve as building blocks for synthesizing biodegradable polymers (P4HB and PBST), providing substantial environmental benefits.