SEMICONTINUOUS HETEROPHASE POLYMERIZATION AS A TOOL FOR PREPARING ULTRAFINE NANOPARTICLES OF IBUPROFEN-POLY(METHYL METHACRYLATE)

Ibuprofen-loaded poly(methyl methacrylate) nanoparticles with mean diameters smaller than 20 nm were prepared by a novel method. This consists in carrying out a semicontinuous heterophase polymerization, in which a solution of drug-monomer is added on a micellar solution at an appropriate dosing rate. Scanning transmission electron microscopy (STEM) measurements showed number-average diameters in the range 16–19 nm with 1.14–1.15 in polydispersity, determined as the ratio of weight-average to number-average diameter. Drug contents in nanoparticles close to 24% were determined by UV-Vis spectrophotometry, confirming the results obtained from a procedure that combines latex filtration and quasielastic light scattering (QLS) measurements. Differential scanning calorimetry (CDSC) determinations suggest that at the ibuprofen contents attained in this study, crystals and dispersed molecules of the drug coexist inside the nanoparticles. Based on the relative simplicity of the process it is expected that its use ...