Ring-Opening Polymerization of ε-Caprolactone and l -Lactide Using Aluminum Thiolates as Initiator
2001; American Chemical Society; Volume: 34; Issue: 3 Linguagem: Inglês
10.1021/ma0014719
ISSN1520-5835
AutoresChing‐Huei Huang, Fa-Cherng Wang, Bao‐Tsan Ko, Te‐Liang Yu, Chu‐Chieh Lin,
Tópico(s)Organoboron and organosilicon chemistry
ResumoPolyesters containing thiolate chain end were obtained from the "controlled" ring-opening polymerization (ROP) of ε-caprolactone or δ-valerolactone initiated by several novel aluminum thiolates. The initiators, [(MOBT)2AlR] (1, R = Me; 2, R = Cl) can be obtained in high yield from the interaction of Me3Al or Et2AlCl with 2 molar equiv of 2-methoxybenzenethiol (MOBT-H). [(μ-TMBM)AlR2]2 (3, R = Et; 4, R = Me; 5, R = Bui) were prepared from the reactions of R3Al with 1 molar equiv of 2,4,6-trimethylbenzylmercaptan (TMBM−H) in dichloromethane at ambient temperature. The X-ray structures of 1−3 have been determined and have shown that 1 and 2 are monomeric while 3 is dimeric in the solid state. The "controlled" character of the aluminum complex shown in the polymerization process has enabled us to synthesize a P-δ-VL-b-P-ε-CL block copolymer, and the thioester end group may provide a suitable method for the design of PCL conjugates. In addition, ROP of l-lactide initiated by 1 can be achieved under refluxing toluene conditions.
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