Ring-Opening Polymerization of Cyclic Esters

Ring-opening polymerisation (ROP) of cyclic esters constitutes a vital methodology for producing aliphatic polyesters with applications ranging from biodegradable plastics to high-performance materials. By cleaving the intramolecular ester bond of monomers such as lactones and lactides, ROP affords control over molecular weight, dispersity and polymer microstructure. Advances in catalyst design—including organometallic, organocatalytic and heterometallic systems—have enabled precise stereocontrol and rapid polymerisation under mild conditions. Thermodynamic factors such as monomer ceiling temperature guide the equilibrium between polymer formation and depolymerisation, facilitating chemical recycling. Recent work has focused on tailoring monomer substitution patterns to regulate thermal and mechanical properties, developing synergistic metal–metal cooperativity for enhanced rates and selectivity, and integrating depolymerisation strategies to close the polymer loop. The global significance of ROP of cyclic esters lies in its potential to deliver sustainable, high-performance materials and circular‐economy processes.

Research from Nature Portfolio

Recent studies have systematically investigated the influence of substituents on ε-caprolactone derivatives to tune polymer thermodynamics and recyclability. By varying substituent size and position, researchers have demonstrated control over ceiling temperatures, extending thermal stability up to 240 °C and enabling selective depolymerisation. Spirocyclic acetal-functionalised monomers have been shown to undergo efficient ROP and depolymerise to monomer under mild conditions, yielding polymers with ductile mechanical behaviour comparable to polypropylene. In parallel, advances in catalyst architecture have revealed that heterometallic cooperativity can substantially enhance both rate and stereocontrol in ring-opening co-polymerisation of cyclic esters and carbonates. Detailed structure–activity relationships have guided the design of bimetallic systems that outperform their homometallic analogues in activity and isoselectivity, providing a blueprint for next-generation catalysts.

Ring-Opening Polymerization of Cyclic Esters publication trend

The graph below shows the total number of articles in ring-opening polymerization of cyclic esters across all publications each year (not limited to Nature Index journals).

Technical terms

Ring-Opening Polymerisation (ROP): a mechanism by which cyclic monomers open to form linear polymers through the cleavage of ring bonds.

Cyclic ester: a monomer with an intramolecular ester linkage forming a ring, such as lactones or lactides.

Ceiling temperature (Tc): the minimum temperature at which polymerisation and depolymerisation are thermodynamically balanced.

Heterometallic catalyst: a catalyst comprising two or more different metal centres that work cooperatively to enhance activity or selectivity.

Stereoselectivity: the preferential formation of polymer chains with defined stereochemical configurations.

Chemical recycling: the depolymerisation of polymers back to their monomer units for repeated polymerisation cycles.

References

1. Insights into substitution strategy towards thermodynamic and property regulation of chemically recyclable polymers. Nature Communications (2023).
2. Advances in heterometallic ring-opening (co)polymerisation catalysis. Nature Communications (2021).
3. Synthesis of Biodegradable Polymers: A Review on the Use of Schiff-Base Metal Complexes as Catalysts for the Ring Opening Polymerization (ROP) of Cyclic Esters. Catalysts (2020).
4. Highly active Mg( ii ) and Zn( ii ) complexes for the ring opening polymerisation of lactide. Polymer Chemistry (2018).
5. “Like Recycles Like”: Selective Ring‐Closing Depolymerization of Poly(L‐Lactic Acid) to L‐Lactide. Angewandte Chemie International Edition (2022).