Metal-Free Synthesis of Tough PLLA- b -PCVL- b -PLLA Triblock Polyester Thermoplastic Elastomers from Mixed Monomers

Designing thermoplastic elastomers (TPEs) that are simultaneously biodegradable, metal-free, and mechanically robust remains a major challenge. Here, we report a one-pot organocatalytic ring-opening polymerization strategy that converts a mixed feed of ε-caprolactone (CL), δ-valerolactone (VL), and l-lactide (LLA) into high-molecular-weight PLLA-b-PCVL-b-PLLA triblock copolyesters without metal catalysts. By exploiting the intrinsic reactivity differences among the monomers and switching from di