Ring-opening polymerization of ε-caprolactone and δ-valerolactone using new Sm(III) μ-halo-bis(trimethylsilyl)amido complexes
✍ Scribed by Seema Agarwal; Marc Karl; Kurt Dehnicke; Gert Seybert; Werner Massa; Andreas Greiner
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 173 KB
- Volume
- 73
- Category
- Article
- ISSN
- 0021-8995
No coin nor oath required. For personal study only.
✦ Synopsis
New Sm(III) -halo-bis(trimethylsilyl)amido complexes [Sm(-X) {N(SiMe 3 ) 2 } 2 (THF)] 2 (X ϭ Cl, Br) were synthesized and their crystal structures were analyzed. These complexes were used as catalysts for the homopolymerization of -caprolactone and ␦-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 (ϳ 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 -halo-bis-(trimethylsilyl)amido complexes and -caprolactone by 1 H-NMR and 13 C-NMR spectroscopic techniques and revealed the presence of more than one initiating species.