Crystallinity and properties of C60 nanotubes improved by annealing and alcohol soaking
Well uniformed C60 nanotubes were grown at 20 ?C with irradiation of red light using C60 saturated pyridine solution and isopropyl alcohol by a liquid liquid interfacial precipitation method without ultrasonic pulverization. We attempted to improve their crystallinity by two post treatments; thermal annealing and alcohol soaking. The crystallinity of as grown and dried C60 nanotubes, which was poor due to the evaporation of solvent molecules from crystals in the drying process, was improved by annealing around 220 ?C for 5 hours in vacuum. Dramatic improvement of crystallinity of as grown samples was achieved by soaking into methanol and then drying in air. Raman, infrared and X ray diffraction results suggest that the methanol soaked samples exhibit a solvated tetragonal structure. The crystallinity improved by methanol soaking did not degrade after removal of methanol molecules from samples by thermal annealing. Photo polymerization of the structurally improved C60 nanotubes was examined to investigate an effect of crystallinity on the polymerization kinetics.