Living Ring-Opening Homo- and Copolymerization of ε-Caprolactone and l- and d,l-Lactides by Dimethyl(s

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• 作者：Daniela Pappalardo ; Liana Annunziata ; Claudio Pellecchia
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：August 25, 2009
• 年：2009
• 卷：42
• 期：16
• 页码：6056-6062
• 全文大小：795K
• 年卷期：v.42,no.16(August 25, 2009)
• ISSN：1520-5835

文摘

The dimethylaluminum compounds {3-tBu-2-(O)C₆H₃CH═N−R}AlMe₂ [R = C₆H₅ (1); 2,6-iPr₂C₆H₃ (2); C₆F₅ (3)] were used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone, l-lactide, and d,l-lactide. Compound 3, in combination with 1 equiv of methanol, exhibited a living behavior in the ROP of the cyclic esters. Such a feature allowed the preparation of poly(d,l-lactide-block-ε-caprolactone) and poly(l-lactide-block-ε-caprolactone) copolymers. Random copolymers of ε-caprolactone and l-lactide and of ε-caprolactone and d,l-lactide were also synthesized by compound 3. NMR and DSC characterization confirmed a highly random structure of these copolymers, even in the absence of transesterification reactions. All the materials, characterized by GPC, showed high molecular weight and narrow molecular weight distributions.