Polymerization of lactides and lactones. III. Ring-opening polymerization of DL-lactide by the (eta(3)-C3H5)(2)Sm(mu(2)-Cl)(2)(mu(3)-Cl)Mg(tmed)(mu(2)-Cl)Mg(tmed) complex

Ring-opening polymerization of DL-lactide (LA) has been initiated with the (eta(3)-C3H5)(2)Sm(mu(2)-Cl)(2)(mu(3)-Cl)(2)Mg(tmed)(eta(2)-Cl)Mg(tmed) com plex 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 (eta(3)-C3H5 )(2)Sm(mu(2)-Cl)(2)(mu(3)-Cl)(2)Mg(tmed)(mu(2)-Cl)Mg(tmed) was more effecti ve for the polymerization of LA, and high molecular weight of polylactide w as obtained by this initiator. The solvent affected the polymerization sign ificantly. The polymerization mechanism was in agreement with the coordinat ion mechanism. The polymer was characterized by FTIR, H-1-NMR, and DSC. (C) 1999 John Wiley & Sons, Inc.