Preparation of PLA microparticles by ASES technique
Poly lactic acid(PLA) microparticles were prepared by a supercritical fluid method, called the aerosol solvent extraction system method.The effects of pressure, temperature, PLA solution concentration and its flow rates,and PLA molecular weight (M_w) on the morphology and particle size (PS) of the resulting PLA microparticles were investigated.The results showed that a viscous film was found at sinter filter fixed on the bottom of the precipitator when M_w was 100000, or PLA solution concentration was 1 g·ml -1, when M_w was less than 100000 or PLA solution concentration was smaller than 1 g·ml -1, PLA microparticles were produced.In the scope of study here, pressure and temperature were the most significant factors on PS, and increasing pressure, or decreasing temperature could lead to a significant decrease in PS.At 20 MPa,35℃,PLA flow rate 240 ml·h -1,concention 0.1 g·ml -1, M_w=10000, the PLA microparticles with a PS of 200～600 nm were successfully obtained.XRD suggested that there was no significant change in crystalline type, but significant decrease in the crystallinity of the resulting PLA products was observed.