期刊
MACROMOLECULAR RAPID COMMUNICATIONS
卷 42, 期 3, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/marc.202000491
关键词
chiral binuclear aluminum catalyst; isoselective; rac‐ lactide; ring‐ opening polymerization
资金
- National Natural Science Foundation of China [21774042, 21871107, 21975102, 22071077]
The study successfully synthesized five chiral binuclear aluminum methyl complexes, which catalyze the ring-opening polymerization of rac-lactide in a controlled manner and produce polymers with high isoselectivity. The kinetic studies show a first-order dependence on monomer concentration, supporting an enantiomorphic site control mechanism for the catalysts. This strategy can also be applied to other lactones for ring-opening polymerization.
The microstructure can significantly affect the physical and mechanical properties of polymers. Five chiral binuclear aluminum methyl complexes (rac1 to rac5) are synthesized by using chiral binaphthalene diamine ligand and characterized by both H-1 and C-13 NMR spectroscopy. The crystal structures of rac3 and rac5 are also identified by single crystal X-ray diffraction. In the presence of (PrOH)-Pr-i initiator, these aluminum complexes catalyze the ring-opening polymerization (ROP) of rac-lactide (rac-LA) in a controlled manner and produce polymers with high to excellent isoselectivity (P-m up to 0.93). Even with a catalyst loading as low as 0.1%, polylactide with a P-m of 0.83 can still be obtained. Kinetic studies reveal the first-order dependence on monomer concentration whereas kinetic resolution polymerization provides the evidence to support that these binuclear aluminum catalysts catalyzed ROP of rac-LA adopts enantiomorphic site control mechanism. Furthermore, this strategy can also be applied to the ROP of both epsilon-caprolactone and delta-valeroactone.
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