Facile synthesis of closed-loop recyclable and crystalline stereoregular poly(ether-

The microstructure of closed-loop recyclable polyesters, including substituent pattern, stereoregularity, and sequence distribution, plays a pivotal role in determining their thermal and mechanical properties. While stereoregular recyclable polyesters exhibit significantly enhanced overall performance, large-scale access to these materials remains challenging. Herein, we report a scalable one-pot synthesis of enantiopure 3-methyl-1,4-dioxan-2-one (αMDO) from bio-based commodity methyl lactate and ethylene oxide. Further controlled ring-opening polymerization (ROP) of the enantiopure αMDO proceeds with retention of the monomer stereochemistry, yielding semicrystalline closed-loop polyesters with melting temperature up to 100 °C, substantially higher than those of polyesters derived from γ- and δ-substituted MDOs. Moreover, thermodynamic investigations reveal that αMDO exhibits more favorable polymerization thermodynamics than γ- and δ-substituted MDOs, enabling controlled ROP under milder conditions. Crucially, the polyesters enable efficient bulk depolymerization to recover the pristine enantiopure monomer, thus offering a practical pathway toward formation of high-performance, closed-loop recyclable polyesters from sustainable commodity feedstocks.