Iron(Ⅲ)acetylacetonate[Fe(aeac)3] was used as catalyst for the ring-opening polymerization of D

L-lactide and copolymerization of D

L-lactide with polyethylene glycol (PEG)．The effects of catalyst content

reaction temperature

polymerization time and D

L-lactide/PEG molar ratio were investigated．It was showed that the polymerization conversion of lactide more than 90％ could be obtained and polylactide (PDLLA) with viscosity-average molecular weight up to 66000 was prepared．Experimental results indicated that the ring-opening polymerization of lactide proceeded via a coordination-insertion mechanism．Analysis by 1H-NMR showed that PEG acted as an initiator participated in initiation of the ring-opening polymerization of lactide

while Fe (acac)3 promoted the esterification of PEG with lactide．The lactide chains grew from both ends of the PEG molecules and ended with hydroxy-terminated lactyl units．