Aerosol synthesis of nanostructured, ultrafine fullerene particles

Aerosol synthesis methods for the production of nanostructured fullerene particles have been developed. The nanostructured, ultrafine fullerene particles were produced by vapor condensation and aerosol droplet drying and crystallization methods in tubular laminar flow reactors. The formation mechanisms were studied by measuring particle-size distributions is the gas phase. High-resolution scanning and transmission electron microscopy methods were used to observe particle morphology and crystal structure, and to study the crystallization mechanisms of the fullerene particles. The production conditions of fullerene particles during synthesis, i.e. gas temperature and flow profiles in the reactor, were evaluated using computational fluid dynamics calculations. In order to study the role of fullerene vapor during crystallization, fullerene particle evaporation dynamics in the laminar flow was modeled using aerosol particle evaporation theory. In addition, a high-performance liquid chromatography method was utilized to study whether it was possible to separate different fullerenes during aerosol processes. The study demonstrated that ultrafine (30–60 nm) fullerene particles can be generated by vapor condensation in a continuous-flow reactor. The size of the fullerene particles can be controlled by varying the reactor temperature. The ultrafine particles are spherical, solid and polycrystalline at processing temperatures of 500 °C and above. The larger fullerene particles with sizes around 100 nm were produced via an aerosol droplet drying method, starting from fullerene-toluene solution droplets. The particles are roughly spherical with pores and voids, and are nanocrystalline when produced at low reactor operating temperatures (20–200 °C). At higher temperatures of up to 400 °C, the particles are denser and mostly polycrystalline. The crystallinity of a fullerene particle can be controlled by changing the reactor operating temperature during the aerosol droplet drying synthesis.