Superstructures and superhydrophobic property in hierarchical organized architectures of fullerenes bearing long alkyl tails

Abstract

Formation of hierarchically self-organized architectures in organic media and their non-wetting surface features of a series of fullerene-C₆₀ derivatives bearing different numbers of long hydrocarbon chains (1–3) and semiperfluoro-alkyl tails (4) are investigated by means of a variety of techniques, including X-ray diffraction, differential scanning calorimetry, as well as spectroscopic and microscopic methods. All derivatives self-assemble into a bilayer arrangement with their fundamental structural subunit and lamellar distance ranging from 2.88 to 4.85 nm depending on the substituents. The hydrocarbon-C₆₀ derivatives (1–3) provide well-defined three-dimensional microparticles having a nanoflaked outer surface morphology or microparticles composed of many plate-like units in 1,4-dioxane solution, both architectures enhancing the surface water-repellency. The microparticles with a nanoflaked-outer surface obtained from a C₆₀ derivative with semiperfluoro-alkyl chains (4) in a diethoxyethane solution exhibit a surface water-repellency comparable to objects formed from the hydrocarbon-hybrid C₆₀ derivatives. Taking into account the moderate hydrophobic nature of the C₆₀ surface compared to the high hydrophobicity of the hydro- or fluoro-carbons, these results suggest that the C₆₀ moieties are exposed to the outer surface in the supramolecular objects formed in polar solvent conditions and define their non-wetting properties.