✦ LIBER ✦

Reactivity of Sm(II) compounds as ring-opening polymerization initiators for lactones

✍ Scribed by Seema Agarwal; Natalia E. Brandukova-Szmikowski; Andreas Greiner

Publisher: John Wiley and Sons
Year: 1999
Tongue: English
Weight: 64 KB
Volume: 20
Category: Article
ISSN: 1022-1336
DOI: 10.1002/(sici)1521-3927(19990501)20:5<274::aid-marc274>3.0.co;2-j

No coin nor oath required. For personal study only.

✦ Synopsis

Successful room temperature ring-opening polymerization (ROP) of e-caprolactone and d-valerolactone has been carried out using SmX 2 (X = I, Br, and cyclopentadienyl (Cp)) catalysts. SmI 2 in the presence of metallic Sm was found to have enhanced reactivity as room temperature ROP initiator for lactones as compared to pure SmI 2 . SmBr 2 and SmCp 2 showed increased reactivity compared with the Sm/SmI 2 system due to their higher reductive power. The catalyst concentration and time of polymerization showed a marked effect on number-average molecular weight (M n ). There was a decrease in M n on increasing reaction time and decreasing catalyst concentration. The initiation mechanism is discussed based on end group analysis of low molecular weight polymers.

📜 SIMILAR VOLUMES

Homoleptic Phosphoraneiminato Complexes

Homoleptic Phosphoraneiminato Complexes of Rare Earth Elements as Initiators for Ring-Opening Polymerization of Lactones

✍ Thorsten Gröb; Gert Seybert; Werner Massa; Frank Weller; Ravi Palaniswami; Andre 📂 Article 📅 2000 🏛 John Wiley and Sons 🌐 English ⚖ 91 KB

Phosphoraneiminato complexes of transition metals containing the NPR 3 À group are known in many coordinationchemical variations [1] as a result of varying bonding modes. In complexes with metal ions in low oxidation states (i, ii) the NPR 3 À group acts as m 3 -N bridging ligand, in medium oxidati

Polymerization of lactides and lactones.

Polymerization of lactides and lactones. II. Ring-opening polymerization of ε-caprolactone and DL-lactide by organoacid rare earth compounds

✍ X. M. Deng; M. L. Yuan; C. D. Xiong; X. H. Li 📂 Article 📅 1999 🏛 John Wiley and Sons 🌐 English ⚖ 144 KB

Ring-opening polymerization of lactone and lactide have been initiated with rare earth organoacid compounds, such as lanthanum acetate in bulk. The polymerization mechanism is in agreement with the "nonionic-coordination-insertion" mechanism, which involves the selective cleavage of the acyl-oxygen

Lithium chloride as catalyst for the rin

Lithium chloride as catalyst for the ring-opening polymerization of lactide in the presence of hydroxyl-containing compounds

✍ Wenhua Xie; Depu Chen; Xiaohong Fan; Jun Li; Peng George Wang; H. N. Cheng; Robe 📂 Article 📅 1999 🏛 John Wiley and Sons 🌐 English ⚖ 135 KB 👁 1 views

Lithium chloride was found to be an effective and biocompatible catalyst for the ring-opening polymerization of lactide in the presence of hydroxyl-containing compounds. Ethylene glycol (EG) and methyl ␣-D-glucopyranoside (MGlc) were used as multifunctional initiators. The polymerization was carried

Calcium Alcoholates of Hydroxytelechelic

Calcium Alcoholates of Hydroxytelechelic Poly(ethylene oxide)s as Initiators for the Ring-Opening Polymerization of 3-(S)-Isopropylmorpholine-2,5-dione

✍ Yakai Feng; Doris Klee; Hartwig Höcker 📂 Article 📅 2001 🏛 John Wiley and Sons 🌐 English ⚖ 110 KB