Ring-opening polymerization of ɛ-caprolactone by lanthanide tris(2,4,6-tri-tert-butylphenolate)s: Characteristics, kinetics and mechanism

✍ Scribed by Lifang Zhang; Yanhui Niu; Yan Wang; Pei Wang; Lijuan Shen

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 224 KB
• Volume: 287
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2008.02.017

✦ Synopsis

Lanthanide tris(2,4,6-tri-tert-butylphenolate)s are highly active initiators for ring-opening polymerization of ε-caprolactone to give polycaprolactone with number average molecular weight as high as 8.3 × 10 4 at 20 • C in 20 min in toluene. The effects of solvent, rare earth element, monomer/initiator molar ratio, monomer concentration, as well as polymerization temperature and time have been investigated. The kinetic studies of ε-caprolactone polymerization have indicated that the polymerization rate is first-order with respect to both monomer and initiator concentrations. The overall activation energy amounts to 39.3 kJ/mol. Mechanistic studies show that the monomer inserts into the growing chain with the acyloxygen bond scission.