Preparation of Poly (L-lactic Acid) Microsphere

Abstract Poly (L-lactic acid) (PLLA) microspheres were prepared by a solvent evaporation method based on an oil/water emulsion. The effect of the mass ratio of PLLA and poly(vinyl alcohol) (PVA) on the formation of the microspheres was discussed, and the influence of extraction speed of dichloromethane on the microsphere morphology was also studied. Moreover, the influences of the PLLA concentration and the volume ratio of water phase to dichloromethane phase were investigated. The results showed that stable microspheres can be obtained under the conditions that the mass ratio of PLLA to PVA is 20:1. Porous microspheres were obtained under faster evaporating speed of dichloromethane. The microsphere size increased with increasing PLLA concentration. The microsphere size also increased with the increase of the volume ratio of water phase to dichloromethane phase. Keywords: microspheremorphologypoly (L-lactic acid)poly(vinyl alcohol)size This work was financially supported by National Natural Science Foundation of China (No. 50604017) and the Foundation of State Key Laboratory for Powder Metallurgy, Central-south University, P.R. China.