# From Molecule to Material: How Support Changes Heterobimetallic Catalysts in Lactide Polymerization

## TL;DR

Scientists developed recyclable catalysts for making polylactide, a sustainable plastic, with precise control over its properties.

## Contribution

New silica-supported heterobimetallic catalysts enable efficient and recyclable lactide polymerization with precise molar mass control.

## Key findings

- Silica-supported [(THF)KFe(OtBu)2]/SiO2-700 and [(THF)NaFe(OtBu)2]/SiO2-700 systems showed high efficiency and recyclability.
- These catalysts produced predictable molar masses with narrow dispersities in lactide polymerization.
- Chain transfer agents improved the precision of polymerization further.

## Abstract

Sustainable production of polylactide demands catalysts that are both recoverable and capable of delivering precise molar mass and stereocontrol. A series of heterobimetallic complexes [(THF)NaFe(OtBu)3]2, [(THF)2KFe(OtBu)3]2, [KZn(OtBu)3]2, [(THF)KCu(OtBu)3]∞ and [(THF)KCo(OtBu)3]2 was evaluated as precursors for heterogeneous catalysts by grafting onto dehydroxylated silica. All complexes demonstrated activity in the ring‐opening polymerization of lactide. Notably, the silica‐supported [(THF)KFe(OtBu)2]/SiO2‐700 and [(THF)NaFe(OtBu)2]/SiO2‐700 systems exhibited high efficiency, promising recyclability, and afforded predictable molar masses (M
n,exp close to M
n,th) with narrow dispersities. These findings highlight new opportunities for designing recyclable catalysts for sustainable PLA synthesis.

Silica‐supported heterobimetallic alkoxide complexes were developed as catalysts for lactide ring‐opening polymerization. Grafting iron‐based ate complexes onto SiO2‐700 produced well‐defined active sites, enabling controlled polymerization with predictable molar masses, narrow dispersities, and recyclability. Incorporating chain transfer agents further improved precision. This strategy offers a robust platform for sustainable polylactide synthesis and future bio‐based polymer applications.