PREPARATION OF AQUEOUS POLYMERIC NANODISPERSIONS BY A REVERSIBLE SALTING-OUT PROCESS - INFLUENCE OF PROCESS PARAMETERS ON PARTICLE-SIZE

Polymeric nanoparticles were prepared as aqueous dispersions using an emulsion technique involving a salting-out process which avoids surfactants and chlorinated solvents. The preparation method consists of adding an electrolyte-saturated or a nonelectrolyte-saturated aqueous solution containing poly(vinyl alcohol) (PVAL) as a viscosity-increasing agent and stabilizer to an acetone solution of polymer under continuous stirring. The saturated aqueous solution prevents acetone from mixing with water by a salting-out process. After the preparation of an oil-in-water emulsion, water is added in a sufficient amount to allow complete diffusion of acetone into the aqueous phase, inducing the formation of nanospheres. Several manufacturing parameters were varied: stirring rate, internal/external phase ratio, concentration of polymer in the acetone phase, type of electrolyte, concentration and type of PVAL in the aqueous phase.