Abstract
L-poly(lactic acid)(PLA) microspheres have been produced by particles from gas saturated solutions(PGSS). A CO2 saturated polymer solution containing ethanol is sprayed through a nozzle to air and/or aqueous solution. In this work, to control the particle morphology, the gas saturated polymer solution is expanded through the nozzle to water. After sprayed through a nozzle to air, polymeric fibers and coalescence particles were obtained. On the other hand, polymeric microspheres were obtained after sprayed through a nozzle to water. The particles were smaller than those produced by PGSS into air. Dispersion of polymeric particles in water impedes particles growth and agglomeration. The particles do not tend to agglomerate after expansion, since the ethanol used as cosolvent on the surface of particles diffuse through the water. The changing the pre-expansion pressure, nozzle diameter, and injection distance between the nozzle and water interface, controls the particle size distribution and morphology of microparticles.
