Stable Colloidal Dispersions of Fullerenes in Polar Organic Solvents

Abstract

Colloidal dispersions of C60 and C70 were prepared by simply mixing a fullerene solution in a good solvent with a poor polar organic solvent for fullerenes. 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 fullerene particles were studied mainly with dynamic light scattering and high-resolution transmission electron microscopy. The most interesting findings are the long-term colloid stability of the samples in the absence of any stabilizers, the relatively narrow size distribution, and the different average sizes of the particles formed by C60, C70, and their mixtures. The influence of various factors such as fullerene concentration, mixing procedure, solvent properties, and C60/C70 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 crystalline structure. The measured negative values for the electrophoretic mobility of the particles suggest that fullerene dispersions in polar organic solvents are stabilized by repulsive electrostatic interactions.

Towards better understanding of C60organosols

“…5,11,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In highly polar organic solvents, the molecular solubility of fullerenes is negligible, 14,15 but they readily form colloidal solutions. [9][10][11][12][13][14][31][32][33][34][35] The state of fullerenes, either molecular or colloidal, in the so-called 'good' or 'strong' solvents, such as CS 2 , toluene, and benzene, is still a matter of discussion. 8,10,11,14,[36][37][38][39][40] Some authors believe that in such a case, aggregates appear only as a result of sonication.…”

“…8,38,41 In contrast, in polar or 'poor' organic solvents, the formation of colloidal species is undoubtedly proven. 9,[11][12][13][14][31][32][33][34][35] Typical examples are aggregates in N-methylpyrrolidin-2-one-acetonitrile mixed solvent, 3 toluene (benzene) mixtures with acetonitrile, 9,12,36 N-methylpyrrolidin-2-one 11,33 and other polar solvents, 13 DMSO, 31 acetonitrile, acetone, ethanol, methanol, and other polar solvents. 32,35,42 Though the stability and coagulation of aqueous C 60 colloids via electrolytes has been examined in full, 14,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][43][44][45][46][47][48][49] the corresponding research for organosols is absent to the best of the authors knowledge.…”

“…10 À30 or less. Then, naturally, the C 60 disproportionation resulting in formation of the C 60 À species 38 or electron transfer from the solvent 32 should be assumed; however, the mechanism demands clarification.…”

Relation Between Nanomorphology and Performance of Polymer-Based Solar Cells

“…(Alargova et al, 2001) Solvents, distinctly dissolving one component of the blend, induce the aggregation of nanofibers and nanoparticles in the solvent prior to film deposition. (Yao et al, 2008) It was shown that (independent of the concentration of the additive) fullerene molecules crystallized into distributed aggregates in the presence of a "bad" solvent in the host solvent.…”

“…9) it was shown that the PCE improves almost by a factor of two. (Alargova et al, 2001;Peet et al, 2007) Fig. 10.…”