Water assisted growth of C₆₀ rods and tubes by liquid-liquid interfacial precipitation method

C₆₀ nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C₆₀/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C₆₀ tubes where both length and diameter of the C₆₀ tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C₆₀ rods and tubes based on the diffusion rate of the good C₆₀ containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 °C at a pressure < 1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.