Characterizing the Impact of Preparation Method on Fullerene Cluster Structure and Chemistry

Abstract

We examined the physical and chemical characteristics of colloidal dispersions of fullerene materials (nC60) produced through several solvent exchange processes and through extended mixing in water only. The nC60 produced via the different methods were unique from each other with respect to size, morphology, charge, and hydrophobicity. The greatest dissimilarities were observed between the nC60 produced by extended mixing in water alone and the nC60 produced by solvent exchange processes. The role of the respective solvents in determining the characteristics of the various nC60 were attributed to differences in the solvent-C60 interactions and the presence of the solvent as a residual in the nC60 structure, indicating the significance of the solvent properties in determining the ultimate characteristics of the colloidal fullerene. Thus, fullerene C60 that may become mobilized through natural processes (agitation in water) may behave in dramatically different ways than those produced through more artificial means. These results highlight the difficulties in generalizing nC60 properties, particularly as they vary in potential toxicity considerations.

Towards better understanding of C60organosols

“…16,17 Elimelech and his co-workers also reported less negative z values of C 60 hydrosols with CaCl 2 as compared with those in NaCl or KCl solutions, but no re-charging was registered. [18][19][20] It is therefore expected that further study of the coagulation of C 60 colloids in various polar organic solvents will provide insight into the nature of both organosols and hydrosols.…”

“…The numerous and sometimes conflicting results of experimental 5,14,[16][17][18][19][20][21][22][23][24][25][43][44][45][46][47][48][49] and theoretical [73][74][75][76][77][78][79] investigations demand such a comparison. Indeed, the theoretical calculations often predict strong interaction between C 60 and water (as a recent example, the work by Choi et al 77 may be proposed), which may be considered as a type of expressed hydration, whereas the coagulation data indicate the hydrophobic nature of the fullerene hydrosols.…”

“…16,17 The first one was obtained from the CCC values of the hydrosol, whereas the second value originates from the data for carbon nanotubes. The DLVO approach in its classical version takes into account the energy of electrostatic repulsion and molecular attraction, the latter being expressed by the combination of Hamaker constants of the solute and solvent.…”

“…[8][9][10][11][12][13][14] While in low-polar aromatic solvents, fullerenes are well solvated and relatively well dissolved, 14,15 in water they generate hydrosols and suspensions. 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.…”

“…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. Despite numerous publications describing the preparation procedure, particle size and other properties, the coagulation by electrolytes and the origin of the charge of colloidal species in organic solvents yet stays almost unexplored.…”