ABSTRACT
There has been remarkable progress in the application of supercritical fluids (SCFs) to the processing of pharmaceuticals over the last decade. This has made the publication of this book a timely event, providing a comprehensive overview of the subject. Supercritical fluid technology (1-4) has successfully proved its applicability in the area of polymer processing (5, 6) and to the preparation of drug delivery systems (7). It is advantageous to use supercritical CO2 to prepare such systems because there is no residual solvent in the materials produced, ambient temperature can be used for processing, and it may be possible to obtain, improved performance in drug release applications by altering the materials’ polymer and drug morphologies from those achievable by conventional preparation techniques. Supercritical (sc) CO2 can swell and plasticize glassy polymers, reducing the glass transition temperature. The plasticization of polymers is also accompanied by the swelling of the polymer matrix, with a consequent increase in the free volume of the polymer. Moreover, scCO2 can reduce the melting temperature of semicrystalline polymers. These effects are crucial to the impregnation and modification of polymeric materials. An additional advantage of scCO2 is the possibility of “tuning” solvent properties of CO2, simply by changing pressure. This tunability is crucial for successful tailoring of materials properties and greatly assists in establishing separation routes.
