Towards greener yttrium‐catalyzed ring‐opening polymerization via an all‐terpene reaction concept

Abstract In the context of green chemistry, replacing fossil‐based components with renewable alternatives in polymerization processes represents a key challenge towards more sustainable materials. This work establishes a terpene‐based polymerization system for the synthesis of aliphatic polyesters via yttrium‐mediated ring‐opening polymerization of bio‐based lactones. An aminoalkoxy bis(phenolate) yttrium catalyst was combined with terpene‐derived alcohols as nucleophiles and dl ‐limonene as a renewable solvent, replacing conventional systems based on isopropyl alcohol and toluene. The terpene‐based alcohols ( E )‐geraniol, (1 R ,2 S ,5 R )‐ l ‐menthol and (3 R )‐linalool, differing in steric demand and substitution pattern, were evaluated as initiators and chain transfer agents. Polymerizations of lactones with varying ring‐strain and size (β‐butyrolactone, ω‐pentadecalactone and the terpene‐derived (−)‐menthide) were performed and directly compared to fossil‐based reference systems. All monomers were successfully polymerized under fully terpene‐based conditions, yielding polymers with controllable molecular weights (3.2–44.6 kg mol −1 ), low dispersities ( Đ = 1.1–1.4) and defined end groups. Kinetic studies revealed a strong influence of nucleophile structure and concentration on polymerization characteristics, with increasing chain transfer agent content leading to decreased molecular weights, consistent with an immortal coordination‐insertion mechanism that can enable efficient catalyst utilization and reduced catalyst loadings. The fully terpene‐based systems provided comparable or improved control over the polymerization and end‐group analysis confirmed the incorporation of terpene‐derived initiating groups, enabling subsequent post‐polymerization functionalization via thiol‐ene chemistry. These results demonstrate that renewable nucleophiles and solvents can effectively replace fossil‐based components in rare‐earth metal‐catalyzed ring‐opening polymerization, providing access to sustainable and functionalizable aliphatic polyesters. © 2026 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.