Stable colloidal dispersions of fullerenes in polar organic solvents

Colloidal dispersions Of C-60 and C-70 were prepared by simply mixing a ful lerene solution in a good solvent with a poor polar organic solvent for ful lerenes. The process was very easy and fast and the formation of particles with average diameter in the colloidal range was detected immediately after the components were mixed. The formation and the properties of the, fuller ene particles were studied mainly with dynamic light scattering and high-re solution transmission electron microscopy. The most interesting findings ar e the long-terrn colloid stability of the samples in the absence of any sta bilizers, the relatively narrow size distribution, and the different averag e sizes of the particles formed by C-60, C-70, and their mixtures. The infl uence of various factors such as fullerene concentration, mixing procedure, solvent properties, and C-60/C-70 ratio was investigated. it is shown that the smaller particles are formed when the total fullerene concentration in the good solvent is decreased and that the fullerene particles have crysta lline structure. The measured negative values for the electrophoretic mobil ity of the particles suggest that fullerene. dispersions in polar organic s olvents are stabilized by repulsive electrostatic interactions.