Unsymmetrical N-Heterocyclic Carbene: 1-Isopropyl-3-benzylimidazol-2-ylidene as Catalyst for Ring-Opening Polymerization of ε-Caprolactone

作者：Zhang, Lifang^*; Wang, Zhenzhong; Wang, Junwen; Wang, Yan; Liu, Chunling

来源：Journal of Macromolecular Science, Part A: Pure and Applied Chemistry , 2012, 49(6): 528-532.

DOI：10.1080/10601325.2012.676934

• 1-Isopropyl-3-benzylimidazol-2-ylidene
• ring-opening polymerization
• epsilon-caprolactone

An unsymmetrical N-heterocyclic carbene, namely 1-isopropyl-3-benzylimidazol-2-ylidene, is a highly active catalyst for ring-opening polymerization of epsilon-caprolactone (CL) to give polycaprolactone (PCL) with number average molecular weight (Mn) as high as 2.66 x 10(4) at 0 degrees C in 100 min in tetrahydrofuran (THF). The effects of monomer/initiator molar ratio ([M]/[I]), catalyst/initiator molar ratio ([C]/[I]), monomer concentration, as well as polymerization temperature and time have been investigated. The kinetic studies of CL polymerization have indicated that the polymerization rate is first-order with respect to both monomer and catalyst concentrations. The apparent activation energy amounts to 56.04 kJ/mol. The proposed mechanism is a monomer-activated process.

• 出版日期2012
• 单位陕西师范大学; 山西师范大学