Polymerization of lactides and lactones: VII. Ring-opening polymerization of lactide by rare earth phenyl compounds

Ring-opening polymerization of D,L-lactide has been initiated with rare earth phenyl compound in bulk and solution. These rare earth phenyl initiators can give high yield and high molecular weight poly(D,L-lactide) (PLA) products. The effects of polymerization conditions, such as reaction time, reaction temperature, monomer/initiator molar ratio on the polymerization have been discussed. The results show that reaction conditions have great influence on the yield and molecular weight of PLA. High molecular weight of PLA is usually obtained in the case of lower M/I molar ratio. The resulting PLA was elaborated in microspheres, and the degradation test in vitro was carried out in pH 7.4 buffer solution at 37°C.