Highly active and stereoselective zirconium and hafnium alkoxide initiators for solvent-free ring-opening polymerization of rac-lactide.
نویسندگان
چکیده
Under solvent-free conditions (at 130 degrees C), zirconium and hafnium amine tris(phenolate) alkoxides are extremely active, well-controlled, single-site initiators for the ring-opening polymerization of rac-lactide, yielding highly heterotactic polylactide.
منابع مشابه
A robust zirconium N-heterocyclic carbene complex for the living and highly stereoselective ring-opening polymerization of rac-lactide.
A readily accessible and robust Zr-NHC complex was found to polymerize rac-lactide in a highly controlled, living and stereoselective manner to afford heterotactic PLA.
متن کاملZinc-Catalyzed Highly Isoselective Ring Opening Polymerization of rac-Lactide
A family of chiral zinc amido-oxazolinate complexes are shown to be highly active and isoselective initiators for the ring-opening polymerization (ROP) of rac-lactide, yielding isotactic stereoblock polylactides (PLA) with Pm up to 0.91. This represents the highest isoselectivity observed with zinc-based catalysts for ROP of rac-lactide.
متن کاملGroup 4 metal initiators for the controlled stereoselective polymerization of lactide monomers.
Group 4 metal initiators with a tetradentate bis(phenolato) ligand polymerized meso-lactide efficiently under ring-opening to give syndiotactic polylactide. L-Lactide was converted faster than rac-lactide and meso-lactide.
متن کاملRobust chiral zirconium alkoxide initiators for the room-temperature stereoselective ring-opening polymerisation of rac-lactide.
Chiral Schiff bases (1H to 4H) and a series of their Group 4 metal alkoxide complexes [(R-1)2Ti(O(i)Pr)2, (R-2)2Ti(O(i)Pr)2, (R-1)(2)Zr(O(i)Pr)2, (R-2)2Zr(O(i)Pr)2, (R-3)2Zr(O(i)Pr)2, (R-4)2Zr(O(i)Pr)2, (S-1)2Zr(O(i)Pr)2 and (rac-1)2Zr(O(i)Pr)2] have been prepared and characterised by 1H, and 13C NMR spectroscopy. In solution, both Lambda and Delta isomers were observed, suggesting a low degree...
متن کاملRing-Opening Polymerization of rac-Lactide with Aluminum Chiral Anilido-Oxazolinate Complexes
A series of dimethylaluminum complexes (L1a-i )AlMe2 (2a-i, where HL1a-i = 2-(2'-ArNH)phenyl-4-R1-oxazoline) bearing chiral, bidentate anilido-oxazolinate ligands have been prepared and characterized. Six of the complexes, in the presence of an alcohol cocatalyst, are shown to be active initiators for the stereoselective ring-opening polymerization of rac-lactide in toluene solution and under b...
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ورودعنوان ژورنال:
- Chemical communications
دوره 11 شماره
صفحات -
تاریخ انتشار 2008