Formation of Polymer Nano-particles in Supercritical Fluid Jets
A.A. Gokhale, B. Khusid, R.N. Dave and R. Pfeffer
New Jersey Institute of Technology, US
supercritical antisolvent process, micro-nozzle, jets, good and poor solvents, nanoparticles
The supercritical antisolvent process is an emerging technology for the production of micro- and nanometer-sized particles for a wide variety of bio-medical pharmaceutical applications. In this method, an organic liquid solution of the compound of interest is sprayed through a nozzle into a chamber containing a highly compressed gas or supercritical fluid (e.g., CO2), which is miscible with the solvent, but is an antisolvent for this compound. The dispersion of the liquid solution in such a medium generates a high degree of supersaturation, leading to the formation of fine, uniform particles. The recovery and separation of the antisolvent from the solvent and solid products is then performed by a simple depressurization step. We study the precipitation of a high-molecular weight Polyvinylpyrrolidone in a binary mixture of a “good”, dichloromethane, and “poor”, acetone, solvents. The solution is injected into a compressed carbon dioxide through a micro-nozzle. The flow regime varies from dripping to spraying. Increasing the acetone content in the solvent is found to suppress the particle aggregation, eliminate their surface irregularities, and decrease the average size. The particle size is also decreasing with decreasing the chamber pressure, the jet velocity, and the nozzle diameter.
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Nanotech 2005 Conference Program Abstract