Ring-opening polymerization of ε-caprolactone and δ-valerolactone using new Sm(III) μ-halo-bis(trimethylsilyl)amido complexes

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Agarwal, Seema ; Karl, Marc ; Dehnicke, Kurt ; Seybert, Gert ; Massa, Werner ; Greiner, Andreas:
Ring-opening polymerization of ε-caprolactone and δ-valerolactone using new Sm(III) μ-halo-bis(trimethylsilyl)amido complexes.
In: Journal of Applied Polymer Science. Bd. 73 (1999) Heft 9 . - S. 1669-1674.
ISSN 1097-4628
DOI: https://doi.org/10.1002/(SICI)1097-4628(19990829)73:9<1669::AID-APP7>3.0.CO;2-1

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Abstract

New Sm(III) mu-halo-bis(trimethylsilyl)amido complexes Sm(mu-X) {N(SiMe3)(2)}(2)(THF)](2) (X = Cl, Br) were synthesized and their crystal structures were analyzed. These complexes were used as catalysts for the homopolymerization of epsilon-caprolactone and delta-valerolactone and found to initiate ring-opening polymerization (ROP) of these monomers in high conversion over a short period, giving homopolymers with a moderate polydispersity index (similar to 2.0). The effect of temperature and the catalyst amount on the molecular weight distribution was also studied. Mechanistic studies were conducted using 1 : 1 and 1 : 6 molar ratios of mu-halo-bis-(trimethylsilyl)amido complexes and epsilon-caprolactone by H-1-NMR and C-13-NMR spectroscopic techniques and revealed the presence of more than one initiating species. (C) 1999 John Wiley & Sons, Inc.