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2010-12-01 - Article/Dans un journal avec peer-review - Anglais - 5 page(s)

De Winter Julien , Coulembier Olivier , Gerbaux Pascal , Dubois Philippe , "High molecular weight poly(a,a',b-trisubstituted b-lactones) as generated by metal-free phosphazene catalysts" in Macromolecules, 43, 24, 10291-10296

  • Edition : American Chemical Society (ACS) (DC)
  • Codes CREF : Chimie macromoléculaire (DI1315), Catalyses hétérogène et homogène (DI1334)
  • Unités de recherche UMONS : Matériaux Polymères et Composites (S816), Synthèse et spectrométrie de masse organiques (S836)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
Texte intégral :

Abstract(s) :

(Anglais) 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 ß-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]-2?5,4?5-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.

Notes :
  • (Anglais) Publiée en ligne le 19 novembre 2010
Identifiants :
  • DOI : 10.1021/ma102123b