Using N2- or CO2-Assisted Atomization Process to Produce Polyethylene Glycol Microparticles

Supercritical anti-solvent (SAS)-atomization technology was used to produce polyethylene glycol (PEG) 6000 microparticles from PEG/acetone solutions; the solutions were atomized through a coaxial nozzle under high pressure CO2 or N2 into a precipitator with atmospheric pressure. The effects of pre-expansion pressure (4 to 12 MPa), flow rate of the PEG/acetone solution (1-7 ml min−1), PEG concentration in the solution (20-80 mg ml−1) and nozzle size (80, 100 and 120 μm) on the particle morphology and particle size were investigated at 50°C. The particles were further characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetry (TG). Results showed that both the N2-assisted and the CO2-assisted atomization processes could generate fine PEG particles with mean sizes of 1-5 μm under optimum operating conditions, and no obvious difference could be found in acetone residue, crystallinity and melting point for the particles obtained from the two processes. Results also revealed that spherical, irregular, agglomerated particles with relatively larger standard deviation were obtained from the CO2-assisted atomization process, while the morphology of particles obtained from the N2-assisted atomization process was not sensitive to the operating conditions due to the inert nature of N2.