Nanoparticles Production by Supercritical Techniques

Poster presentato a Euronanoforum , Trieste (I), 9-12 dicembre 2003. - Numerous supecritical fluids (SCF) techniques have been proposed to produce microparticles. They have been developed to overcome the limits of traditional micronization techniques in which it is problematic or impossible, to produce micronic or submicronic particles using jet milling, ball milling and liquid antisolvent crystallization. For these applications, carbon dioxide (SC-CO2) is the most common SCF choice. For different industrial fields (such as semiconductors, drug release systems, catalysts) it has been used in several techniques, among the others: - RESS technique, based on the solubilization of a solid to be micronized in SC-CO2 and its subsequent precipitation by fast depressurization of the formed solution: - SAS technique, based on the use of SC-CO2 as antisolvent to precipitate a solid solute from a liquid solution; - SSI technique, based on the impregnation of a polymer matrix by a solute released from a supercritical solution; - Reaction in SF media technique, based on a reaction (hydrolysis) in SF-CO2 to produce nanosized materials - Drying technique, based on a sol-gel synthesis to produce mesoporous materials followed by SC-CO2 drying. In literature, several variations have been applied on these base-techniques to improve the quality of the nanoparticles produced. Examples of the above-mentioned techniques in the production of nanoparticles for pharmaceuticals, catalysts, semiconductors and drug delivery systems are reported.