Copolymerization of l-lactide and ε-caprolactone using aluminum aminobisphenolate as an initiator: a quantum chemical study

The ring-opening homopolymerization and copolymerization of ε-caprolactone (CL) and l -lactide (LA) in the presence of an aluminum complex with aminobisphenolate ligand MeN{CH 2 [(3-Bu t )C 6 H 3 (2-O−)]} 2 Al−OMe (LAl−OMe) was modeled in terms of the density functional theory (DFT). The structures...

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Veröffentlicht in:Russian chemical bulletin 2023-03, Vol.72 (3), p.602-616
Hauptverfasser: Zabalov, M. V., Mankaev, B. N., Egorov, M. P., Karlov, S. S.
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Sprache:eng
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Zusammenfassung:The ring-opening homopolymerization and copolymerization of ε-caprolactone (CL) and l -lactide (LA) in the presence of an aluminum complex with aminobisphenolate ligand MeN{CH 2 [(3-Bu t )C 6 H 3 (2-O−)]} 2 Al−OMe (LAl−OMe) was modeled in terms of the density functional theory (DFT). The structures of transition states and intermediates were optimized for the initiation stage of the polymerization of CL and LA and for the first stage of the chain propagation reactions affording LAl−LA−LA−OMe, LAl−LA−CL−OMe, LAl−CL−LA−OMe, or LAl−CL−CL−OMe. The barriers to the rate-limiting stages were determined. A fundamental reactivity difference between CL and LA was established. It is associated with the formation of a stable chelate intermediate whose stability governs the distribution of monomeric units in the copolymer. The LAl−OMe complex exhibits a rare feature, viz., the polymerization of CL during the copolymerization in the presence of this initiator should proceed faster than the polymerization of LA, which leads to the preferential formation of the poly(CL- block -LA) block copolymer.
ISSN:1066-5285
1573-9171
DOI:10.1007/s11172-023-3824-6