| For the investigation of biological properties, it is necessary to synthesize water soluble C60. There has been increasingly interest in preparation of aqueous solution of fullerene. Ultrasonic process was one of most efficient and simple method to synthesize water soluble C60. This method is first invented by G.V.A., he named the water soluble C60 as FWS (fullerene-water-system). For ultrasonic process, how to obtain disperse and uniform C60 particles and various particles sizes are unresolved problems. This may extend the application field of water soluble fullerene.High pressure and high temperature (HPHT) can change the structure of materials, and thus change the physical properties. It provides us a very powerful tool to study the relations between the structure and physical properties. HTHP is widely used in studying bulk C60 polymerization, but for nano C60 material is a novel subject, for C60FWS nanoparticles have not yet started research. Weather hydrated C60 molecules can joined by covalent 2+2 cycloaddition bands, weather hydrated C60 can formed a Long-range ordered structure under HTHP treatment are an attractive question. The study of C60FWS nanoparticles under HTHP will expand the understanding of the C60 polymerization and C60FWS system.In this letter, we have modified the method of FWS preparation, we were able to adjust the size of the C60FWS. We can obtain uniform and various sizes of the C60FWS and modified the crystallization capacity. And we have studied C60FWS nanoparticles under HTHP treatment.In the process of the experiment, we obtain various sizes and different structure of C60FWS by adjusting the water temperature of the bath of ultrasonic. As the temperature at 60℃, the average size is 45nm. The particles are in narrow size range of 40-55nm and significantly more uniform than the values reported previously with the same method. When temperature falls to 40℃, the average size and the size range are slightly increased. For the above two sample, they are not in a crystalline structure. As the temperature falls to 20℃, the average size obviously increase to 250nm and the size range is wider from 140nm to 300nm. It indicated that the temperature has significant effect on the particle size and crystallization of the FWS particle.For further study, we treat the C60FWS particle synthesized under 60℃and 20℃condition by heating to 200℃, respectively. After heating, the C60FWS particle synthesized under 60℃becomes smaller in size, the mean size of the particle is about 10nm. At the same time, the particles are in a well dispersed state. The C60FWS particle synthesized under 20℃, there is a lot of smaller particles get together, no big aggregates are observed. The above information indicated that the big aggregates consist of the smaller particles when the C60FWS particle synthesized under 20℃.We have studied C60FWS nanoparticles under HTHP. Analyse the change of the structure under HTHP treatment. The C60 FWS is polymerized under quasihydrostatic pressure conditions by using a piston-cylinder device with silicone oil as pressure medium. Raman data indicated that we obtain the dimer phase of C60 polymer.Ultrasonic process was also applied to the synthesis of water soluble C70. Compared with C60FWS particles, it is difficult to control the particle size by adjusting temperature of the bath of ultrasonic. The particle size is in a wide range of 25-300nm. In the PL spectra, the relative intensity is obvious difference between water soluble C70 and bulk C70. |
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