Details

Autor(en) / Beteiligte

• De Winter, Julien
• Coulembier, Olivier
• Gerbaux, Pascal
• Dubois, Philippe

Titel

High Molecular Weight Poly(α,α′,β-trisubstituted β-lactones) As Generated by Metal-Free Phosphazene Catalysts

Ist Teil von

• Macromolecules, 2010-12, Vol.43 (24), p.10291-10296

Ort / Verlag

Washington, DC: American Chemical Society

Erscheinungsjahr

2010

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The use of different phosphazene bases has been investigated as catalysts in polymerization of [R,S]-4-benzyloxycarbonyl-3,3-dimethyl-2-oxetanone (dMMLABz) in presence of carboxylic acids used as initiators. Whatever the catalyst considered (P1-t-Bu, P2-t-Bu, or P4-t-Bu) a very good control over the polymerization has been obtained in terms of polyester molecular weights and end-groups fidelity as attested by spectroscopic techniques such as 1H NMR, gel permeation chromatography (GPC) and matrix assisted laser desorption ionization-mass spectrometry (MALDI−MS) experiments. Characterized by a complete absence of transfer reactions, the system allows for the generation of very high molecular weight PdMMLABz trough a mechanism selectively involving the “O-alkyl” scission of the β-lactone monomer. A clear dependence of the basicity of the phosphazene catalyst on the overall polymerization kinetics has been observed where the most basic catalytic species, i.e., 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranyl-idenamino]-2Λ5,4Λ5-catenadi(phosphazene) (P4-t-Bu), shows the highest active ion-pair. Accordingly, P4-t-Bu allowed for the synthesis of PdMMLABz chains characterized by a number-average molecular weight higher than 1.5 × 106 g mol−1.