Structure And Morphologies Of C₆₀ Fullerene Nanofibers

C₆₀ is a well-known fullerene prototype; zero-dimensionalstructure has been generally accepted for C₆₀ fullerene. If it was possible to modify such a zero dimensionalstructure of C₆₀ into a self assembled one-dimensional(1-D) one, novel optoelectronic and magnetic properties might be expected. The purpose of the research subject is to prepare crystalline fullerene C₆₀ nanofibers (FNFs) by a liquid–liquid interfacialprecipitation (LLIP) method and to obtain the optimized synthesis conditions and possible growth mechanism of fullerene C₆₀ nanoubes ( FNTs).1D FNFs were prepared via LLIP using toluene, m-xylene, pyridine and/or N-methyl-2-pyrrolidone (NMP) as solvents and isopropyl alcohol as the precipitation agent at 8°C. C₆₀-saturated solutions were exposed to visible light to promote the growth of FNFs. When the solvents were toluene and m-xylene, it was difficult to synthesize hollow C₆₀ fullerene nanotubes, or the FNTs. By contrast, the hollow FNTs were easily grown in the C₆₀-pyridine solution or C₆₀-NMP solution upon exposure to visible light. It is found that there is a criticalcorrelation between adducts of the solvents with C₆₀ molecules and the tubular structure of FNFs.We systematically analyzed the irradiation time and wavelength dependence of the mean ratio of inner diameter to outer diameter of FNTs. When irradiated with relatively short wavelength, FNTs with relatively thinner walls, and clear inner diameters were formed. Taking no account of wavelength, when irradiated by 30 min, there is the larger ratio of inner diameter to outer diameter of FNTs, which means relatively largest inner diameter and thinnest tube wall.With the experimentalobservations mentioned in the above section, a possible growth mechanism to describe the formation process of C₆₀ FNTs is proposed: C₆₀-pyridine quasi-surfactant mechanism. We expect to obtain FNTs with different ratios of inner diameter to outer diameter when the C₆₀ suppliers have different equilibrium points. In this study, it is the most favorable condition for the formation of CT complexes between pyridine and C₆₀ molecules when the C₆₀ pyridine solution was irradiated by light with relatively short wavelength and optimum time. After IPA injection, the most stabilized sphere-like fullerene particles with smallest diameters encapsulated by an outer layer of pyridine were formed immediately. Reaching to the equilibrium point easily, these stable fullerene particles are not likely to supply C₆₀ to the centralportion of the tubes because of the outer protect layer of pyridine. As a result, FNTs with relatively thinner walls, and clear inner diameters were formed.