Supercritical CO2-based production of fullerene nanoparticles

Fullerene nanoparticles have potential uses in a variety of applications in cluding pharmaceuticals, lubricants, composite materials, specialized coati ngs, and interfacing membrane surfaces. In this study, the supercritical an tisolvent process is used to reduce fullerene particle size from 40 mu m to as low as 29 nm. C-60 dissolved in toluene is injected into supercritical CO2, causing precipitation of C-60 as fine particles. Because of the high d iffusivity of CO2 in toluene, a rapid supersaturation is achieved, which re sults in the formation of C-60 nanoparticles with a narrow size distributio n. The effect of pressure, temperature, and jet velocity on particle size a nd morphology is studied. The particle size increases linearly with the den sity of supercritical CO2. A high jet velocity yields spherical particles w hereas a lower jet velocity yields both spherical and rodlike particles. In most cases, a uniform thin film of the particles is obtained on the collec tion plate.