Generation of microparticles using CO2 and CO2-philic antisolvents

Precipitation using a compressed antisolvent (PCA) is a demonstrated techno logy for generation of monodisperse ultrafine particles. Microparticle prec ipitation using CO2-philic antisolvents was studied with the ultimate goal of developing fundamental approaches to tailor microparticle generation. Th e ability to micronize small solutes and polymeric systems using CO2-philic liquid antisolvents is compared to precipitation with compressed CO2 and t raditional antisolvents. Analogies are made between PCA and CO2-philic anti solvent precipitation based on thermodynamic driving forces and the dynamic s of the spray process. Analysis of the interfacial gradient energies of th e miscible solvent-antisolvent systems indicates that the spray process is dominated by turbulent mixing and not atomization. The similar microparticl e morphologies of amorphous and semicrystalline poly(lactic acid) (PLA) obt ained using liquid CO(2)(-)philic antisolvents and compressed CO2 suggest t hat a similar demixing mechanism dominates microparticle formation at these operating conditions.