“In Situ” Formation of Yttrium Alkoxides: A Versatile and Efficient Catalyst for the ROP of ε-Caprolactone
2003; American Chemical Society; Volume: 36; Issue: 16 Linguagem: Inglês
10.1021/ma034236+
ISSN1520-5835
AutoresÉric Martin, Philippe Dúbois, R. Jérôme,
Tópico(s)Carbon dioxide utilization in catalysis
Resumo[Tris(hexamethyldisilyl)amide] yttrium is a catalyst for the controlled ring-opening polymerization of e-caprolactone when reacted with an excess of alcohol. Up to an alcohol-to-yttrium molar ratio of 50, the chain transfer to the alcohol is quantitative, and the molecular weight of the chains can be predicted from the monomer-to-alcohol molar ratio. At alcohol-to-yttrium ratios higher than 100, the alcohol is quantitatively consumed provided that 1,1,1,3,3,3-hexamethyldisilazane, which is formed as a byproduct, is removed from the reation medium. Depending on the structure of the alcohol, end-functional polyesters can be prepared (e.g., with N-pyrrolyl and 3-thienyl end groups). Well-defined block and random copolymers of e-CL with lactides and γ-bromo-e-caprolactone, respectively, have also been synthesized. Compared to aluminum alkoxides, the in situ formed yttrium alkoxides have the advantage of a much faster polymerization kinetics while preserving control.
Referência(s)