Highly isotactic polylactide by binary organocatalyzed polymerization of 1,3-dioxolan-4-ones†

Ring-opening polymerization (ROP) of dioxolanones (DOXs) provides access to functional polyesters with properties that are challenging to achieve via traditional polymerization of lactones. However, typical catalysts often induce epimerization in DOXs, limiting the synthesis of isotactic, crystalline polymers. This study reports a binary organocatalytic system that enables controlled ROP of chiral 2,2,5-trimethyl-1,3-dioxolan-4-ones under mild conditions, effectively minimizing epimerization by activating both the monomer and initiator via hydrogen bonding. This strategy facilitates the synthesis of highly isotactic poly(lactic acid) (PLA) with a stereoregularity parameter of 0.92. Moreover, blending enantiomeric PLA chains form a crystalline stereocomplex with a high melting temperature of 195.1 °C. These findings highlight a sustainable and scalable approach for synthesizing stereoregular polyesters, paving the way for advanced material applications.