Polymerization of lactides and lactones. III. Ring-opening polymerization of DL-lactide by the (η3-C3H5)2Sm(μ2-Cl)2(μ3-Cl)2Mg(tmed)(μ2-Cl)Mg(tmed) complex

Ring-opening polymerization of DL -lactide (LA) has been initiated with the (η³-C₃H₅)₂Sm(μ₂-Cl)₂(μ₃-Cl)₂Mg(tmed)(η₂-Cl)Mg(tmed) complex both in bulk and solution. The effects of reaction conditions, such as reaction time, reaction temperature, and monomer/initiator molar ratio on the polymerization has been discussed. The results showed that (η³-C₃H₅)₂Sm(μ₂-Cl)₂(μ₃-Cl)₂Mg(tmed)(μ₂-Cl)Mg(tmed) was more effective for the polymerization of LA, and high molecular weight of polylactide was obtained by this initiator. The solvent affected the polymerization significantly. The polymerization mechanism was in agreement with the coordination mechanism. The polymer was characterized by FTIR, ¹H-NMR, and DSC. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2857–2862, 1999