Polymeric fullerene oxide (fullerene ozopolymers) produced by prolonged ozonation of C 60 and C 70 fullerenes

Abstract

The prolonged ozonation of C 60 and C 70 fullerene produces light brown to brown amorphous solids which are insoluble in chlorinated and hydrocarbon solvents but which are readily soluble in water, acetone and ethanol where they give dark-brown solutions. The polymeric and polyelectrolytic nature of these solids has been shown by viscosimetric and cryoscopic measurements. Due to the polymeric nature the solids have been called ‘ozopolymers’. The reactivity and the ozone uptake have been measured quantitatively during the ozonation of C 60 and C 70 fullerene in CCl 4. Three different C 60 ozopolymer samples have been produced at different degrees of ozonation: at O 3/C 60 molar ratio of 8, 14 and 26. The C 70 ozopolymer has been produced at an O 3/C 70 molar ratio of 30. All the samples have been studied by FT-IR spectroscopy and the C 60 ozopolymers have been easily reduced by the action of Zn dust and acetic acid or by the action of H 2S and studied by FT-IR. The action of oxidizing agents has been studied as well. C 60 ozopolymer is a polyelectrolyte rich in carboxyl groups and for this reason it possesses a high metal binding capacity similar to that of humic acids. The thermal stability of C 60 ozopolymer and its reduced derivatives as well as the thermal stability of C 70 ozopolymer has been checked by thermogravimetric analysis in nitrogen and air flow. Finally, the electrical conductivity of C 60 ozopolymer was found to be σ=2.8×10 −8 S/cm which is three orders of magnitude lower than that of pure C 60.