New Kids in Lactide Polymerization: Highly Active and Robust Iron Guanidine Complexes as Superior Catalysts
Abstract
Polylactide is a biodegradable versatile material based on annually renewable resources and thus CO 2 ‐neutral in its lifecycle. Until now, tin(II)octanoate [Sn(Oct 2 )] was used as catalyst for the industrial ring‐opening polymerization of lactide in spite of its cytotoxicity. On the way towards a sustainable catalyst, three iron(II) hybrid guanidine complexes were investigated concerning their molecular structure and applied to the ring‐opening polymerization of lactide. The complexes could polymerize unpurified technical‐grade rac ‐lactide as well as recrystallized l ‐lactide to long‐chain polylactide in bulk with monomer/initiator ratios of more than 5000:1 in a controlled manner following the coordination–insertion mechanism. For the first time, a biocompatible complex has surpassed Sn(Oct) 2 in its polymerization activity under industrially relevant conditions.
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Tin(ii) octanoate remains the only commercially applied catalyst for the production of polylactide.
“tin(ii)octanoate remains the only commercially applied catalyst for the production of polylactide”
Iron complexes with N-O donor ligands consisting of guanidines fused with benzoate esters give faster rates than their zinc analogues and catalyse lactide polymerisation at similar or even higher rates than Sn(Oct)2 under industrial conditions.
“Recently, iron complexes with N–O donor ligands consisting of guanidines fused with benzoate esters were demonstrated to give faster rates than their zinc analogues and to catalyse lactide polymerisation at similar or even higher rates than Sn(Oct)2 under industrial conditions.”
The iron guanidine complex [FeCl2(TMG5NMe2asme)] (1) polymerizes lactide faster than the industrially used Sn(Oct)2.
“The iron guanidine complex [FeCl2(TMG5NMe2asme)] (1) polymerizes lactide faster than the industrially used Sn(Oct)2 and shows high activity towards glycolide and ϵ‐caprolactone.”
From Master of Chaos and Order: Opposite Microstructures of PCL‐<i>co</i>‐PGA‐<i>co</i>‐PLA Accessible by a Single Catalyst** (2022) · cites this paper as [27]
The catalyst 1 follows the coordination-insertion mechanism.
“Its polymerization properties for lactide in bulk at 150 °C was already investigated, a k p of (0.554±0.024) L mol−1 s−1 was determined and it was shown that the catalyst follows the coordination–insertion mechanism. [27]”
From Master of Chaos and Order: Opposite Microstructures of PCL‐<i>co</i>‐PGA‐<i>co</i>‐PLA Accessible by a Single Catalyst** (2022) · cites this paper as [27]
For lactide polymerization in bulk at 150 °C with 1, kp is (0.554±0.024) L mol−1 s−1.
“Its polymerization properties for lactide in bulk at 150 °C was already investigated, a k p of (0.554±0.024) L mol−1 s−1 was determined and it was shown that the catalyst follows the coordination–insertion mechanism. [27]”
From Master of Chaos and Order: Opposite Microstructures of PCL‐<i>co</i>‐PGA‐<i>co</i>‐PLA Accessible by a Single Catalyst** (2022) · cites this paper as [27]
1 is especially active and stable in melt polymerizations at high temperatures.
“1 is known to be especially active and stable in melt polymerizations at high temperatures. [27]”
From Master of Chaos and Order: Opposite Microstructures of PCL‐<i>co</i>‐PGA‐<i>co</i>‐PLA Accessible by a Single Catalyst** (2022) · cites this paper as [27]
1 is known to act as a single site catalyst.
“1 is known to act as a single site catalyst [27] therefore, the formation of two unconnected homopolymers or species with different compositions produced by ambiguous initiation cannot be excluded.”
From Master of Chaos and Order: Opposite Microstructures of PCL‐<i>co</i>‐PGA‐<i>co</i>‐PLA Accessible by a Single Catalyst** (2022) · cites this paper as [27]
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References 52 · Cited by 82
- Authors
- Rittinghaus, R. D., Schäfer, P. M., Albrecht, P., Conrads, C., Hoffmann, A., Ksiazkiewicz, A. N., Bienemann, O., Pich, A., & Herres‐Pawlis, S.
- Affiliations
- RWTH Aachen University (DE)
- Maastricht University (NL)
- TU Dortmund University (DE)
- Corresponding author
- Herres‐Pawlis, Sonja
- ORCID
- Venue
- ChemSusChem
- Publisher
- Wiley
- Published
- 2019-03-19
- Volume
- 12
- Issue
- 10
- Pages
- 2161-2165
- ISSN
- 1864-5631 (ISSN-L)
- 1864-564X
- OpenAlex
- W2919725392
- Semantic Scholar
- 35af2b91e62e74094b6a03e77b6ced5e9d67a7cc
- Cited by
- 82
- References
- 52
- Citations by year
- 2026: 5 · 2025: 10 · 2024: 11 · 2023: 12 · 2022: 16 · 2021: 11 · 2020: 9 · 2019: 8
- FWCI
- 3.12
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- ChemSusChem (publishedVersion)
- PubMed (publishedVersion)
- Research Publications (Maastricht University) (publishedVersion)
- RWTH Publications (RWTH Aachen) (submittedVersion)
- Research Publications (Maastricht University) (submittedVersion)
- Funders
- Deutsche Forschungsgemeinschaft (SFB985)
- Topics
- Physical Sciences › Materials Science › Biomaterials › biodegradable polymer synthesis and properties
- Physical Sciences › Chemical Engineering › Process Chemistry and Technology › Carbon dioxide utilization in catalysis
- Physical Sciences › Chemistry › Organic Chemistry › Organometallic Complex Synthesis and Catalysis
- Keywords
- polylactic acid, lactide ring-opening polymerization, biodegradable polymers, biocompatible catalysts, coordination-insertion mechanism, L-lactide, rac-lactide, catalytic activity
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