Zwitterionic Ring Opening Polymerization of Lactide by Metal Free Catalysts: Production of Cyclic Polymers

作者：Prasad Aitha Vishwa; Stubbs Ludger Paul; Zhun Ma; Zhu Yinghuai^*

来源：Journal of Applied Polymer Science, 2012, 123(3): 1568-1575.

DOI：10.1002/app.34494

• D-lactide
• L-lactide
• cyclic poly(lactide)
• cyclic polymers
• Zwitterionic polymerization
• ring opening polymerization
• n-heterocyclic carbene catalyst
• organo-catalyst
• metal free catalyst

Tailor made N-heterocyclic carbene (NHC) catalyst precursors namely (+) and (-) 1-methyl-3-menthoxymethyl imidazolium chloride have been synthesized in high yield with a literature modified procedure. A reaction of catalyst precursor with potassium tert butoxide in situ generates the NHC catalyst. The zwitterionic ring opening polymerization of lactide (LA) mediated by a catalytic system composed of NHC catalyst at 25 degrees C under argon atmosphere led to a cyclic poly(lactide) of a high molecular weight with a narrow molecular weight distribution. The cyclic poly(lactide) was characterized by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The NHC catalysts are active for lactide polymerization in the presence of air and elevated temperatures at 55 degrees C.

• 出版日期2012-2-5