Selective Low‐Temperature Depolymerization of Highly Transesterified P(LLA‐ co ‐CL) Copolymers: Efficient Lactide Recovery and PCL Upcycling

ABSTRACT The selective chemical recycling of copolyesters remains a major challenge for achieving polymer circularity. Here we show that highly transesterified poly(L‐lactide‐ co ‐caprolactone) (P(LLA‐ co ‐CL)) copolymers undergo low‐temperature depolymerization with exceptional selectivity for L‐lactide (LLA). Statistical copolymers prepared under SnOct 2 /BnOH at 130 °C feature both lactidyl and lactoyl units, reflecting extensive sequence scrambling. Upon vacuum distillation at 230°C, distillates are recovered that are highly enriched in LLA (up to 96–99 mol%), while the polymer residues reorganize into higher‐molar‐mass polycaprolactone (PCL) chains sporadically decorated with lactoyl units. Further heating to 250°C mobilizes these domains, affording controlled release of CL and its dimer. Importantly, no macrocyclic species incorporating caproyl‐lactidyl or caproyl‐lactoyl motifs were detected, in line with the thermodynamic disfavor of 10‐ and 13‐membered ring formation. Instead, the recycling process combines the selective regeneration of virgin‐quality LLA with the generation of unprecedented “upcycled PCL” architectures, distinct from conventional PCL and offering new opportunities for property design. This dual outcome establishes a practical framework for closed‐loop and value‐added recycling of complex copolyesters.