| abstract |
A process for the preparation of nanoscale particulate material is described comprising: (i) combining one or more functional material to be precipitated as nanoscale particles and one or more surface active material in a compressed CO 2 phase with a density of at least 0.1 g/cc, where the functional material is substantially insoluble in the compressed CO 2 in the absence of the surfactant, the surfactant comprises a compressed CO 2 -philic portion and a functional material-philic portion, and the compressed CO 2 phase, functional material and surfactant interact to form an aggregated system having a continuous compressed CO 2 phase and a plurality of aggregates comprising surfactant and functional material molecules of average diameter less than 10 nanometers dispersed therein; and (ii) rapidly depressurizing the compressed CO 2 phase thereby precipitating the dispersed functional and surfactant materials in the form of composite particles of average diameter from 0.5 to less than 10 nanometers. |