Details

Autor(en) / Beteiligte

• Tufano, Federica
• Santulli, Federica
• Grisi, Fabia
• Lamberti, Marina

Titel

N‐Heterocyclic Carbene‐Based Zinc Complexes: Same Precursors for Different Lactide Ring‐Opening Polymerization Mechanisms

Ist Teil von

• ChemCatChem, 2022-10, Vol.14 (20), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2022

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• Two zinc complexes bearing NHC ligands were synthesized and fully characterized by NMR spectroscopy. Their behavior in the Ring‐Opening Polymerization (ROP) of lactides was investigated under several conditions of reaction. They showed to be efficient initiators, producing polylactides with molecular weights depending on the cocatalysts. Microstructural analysis of poly(rac‐LA) by 1H NMR spectroscopy revealed a slightly enriched‐heterotactic PLAs with Pr values up to 0.66. Inspection of the kinetic parameters for L‐LA and rac‐LA allowed to compare the kobs of the studied complexes 1 and 2 under different conditions, and showed that propagations present the usual pseudo‐first‐order dependence on monomer concentration. Hence, some reactivity studies were carried out, addressed to unravel the nature of the active species in the polymerization processes conducted in the presence of different catalytic systems, namely zinc complexes alone and in combination with neutral or ionic cocatalysts. NHC‐based zinc complexes 1 and 2 are active in the ring‐opening polymerization of lactides, both under mild reaction conditions and under the more challenging industrial conditions, with not purified L‐lactide. Some reactivity experiments have been carried out in order to get information on the nature of the active species generated under different reaction conditions.