A single active site metal center of neodymocene chloride for the ring-opening polymerization of ε-caprolactone

✍ Scribed by Weifeng Hou; Jin Chen; Xiaoli Yan; Zuyun Shi; Junquan Sun

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 216 KB
• Volume: 123
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.34599

✦ Synopsis

A germyl-bridged lanthanocene chloride, Me 2 Ge( t Bu-C 5 H 3 ) 2 LnCl (Ln ¼ Nd; (Cat-Nd), was prepared and successfully used as single catalyst to initiate the ringopening polymerization of e-caprolactone (e-CL) for the first time. Under mild conditions (60 C,[e-CL]/[Ln] ¼ 200, 4 h), Cat-Nd efficiently catalyzes the polymerization of e-CL, giving poly(e-caprolactone) (PCL) with high molecular weight (MW) (>2.5 Â 10 4 ) in high yield (>95%). The effects of molar ratio of [e-CL]/Cat-Nd, polymerization temperature and time, as well as solvent were determined in detail. When the polymerization is carried out in bulk or in petroleum ether, it gives PCL with higher MW and perfect conversion (100%). The higher catalytic activity of this neodymocene chloride could be ascribed to the bigger atom in the bridge of bridged ring ligands. Some activators, such as NaBPh 4 , KBH 4 , AlEt 3, and Al(i-Bu) 3 , can promote the polymerization of e-CL by Cat-Nd, which leads to an increase both in the polymerization conversion and in the MW of PCL. V