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|標題:||Air-Stable Copper Derivatives as Efficient Catalysts for Controlled LactidePolymerization: Facile Synthesis and Characterization of Well-DefinedBenzotriazole Phenoxide Copper Complexes||關鍵字:||benzotriazole phenoxide;biodegradable;catalysis;copper;lactide;polyesters;ring-opening polymerization (ROP)||Project:||Journal of Polymer Science Part A: Polymer Chemistry, Volume 51, Issue 18, Page(s) 3840-3849.||摘要:||
Air-stable copper catalysts supported by bis-BTPligands (BTP 5 N,O-bidentate benzotriazole phenoxide) weresynthesized and structurally characterized. The reactions ofCu(OAc)2 H2O with 2.0 molar equivalents of sterically bulky2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol(CMe2PhBTP-H) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-butylphenol(t-BuBTP-H) in refluxing ethanol solution afforded monomericcopper complexes [(CMe2PhBTP)2Cu] (1) and [(t-BuBTP)2Cu] (2),respectively. The four-coordinated copper analogue[(TMClBTP)2Cu] (3) resulted from treatment of 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (TMClBTP-H) as theligand under the same synthetic method with ligand to metalprecursor ratio of 2:1, but treatment of complex 3 in acetonegave five-coordinated monomeric complex [(TMClBTP)2Cu(Me2CO)] (4). X-ray diffraction of single crystals indicates thatCu complex 4 assumes a distorted square pyramidal geometry,penta-coordinated by two BTP ligands, and one Me2CO molecule.Catalysis for lactide (LA) polymerization of BTP-containingCu complexes in the presence of various alcohol initiators wasinvestigated. Complex 3 initiated by 9-anthracenemethanol catalyzesthe ring-opening polymerization effectively not only in a“living” fashion but also in an “immortal” manner, yieldingpolymers with the predictable molecular weights and narrowmolecular weight distributions. Initiations from multifunctionalalcohols were able to produce PLLAs with two-arm linear andthree-arm star-shaped molecular architectures. The controlledcharacter of Cu complex 3 also enabled us to synthesize thePEG-b-PLLA copolymer.
|Appears in Collections:||化學工程學系所|
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