Studies of C₆₀ oxidation and products

Abstract

The oxidation of C₆₀ solid was investigated using TGA, DTA, X-ray diffraction, FTIR, and optical microscopy. oxidation reaction of solid C₆₀ commences at a temperature below 220°C, resulting in the formation of a polycondensate (PCS) with C:O=5:1. The associated heat of formation ΔH_f is determined to be 9.2 kJ/g. From the Isothermal investigations carried out between 220 and 240°C, the reaction mechanism is identified to be a two-dimensional nucleation and growth process. The PCS is found to undergo a structural modification without weight change beyond 220°C with an enthalpy change of 4.6 kJ/g. The PCS itself is found to consist of (1) a glassy carbon with an inter-microfibril distance of 3.78 Å obtained with the destruction of the C₆₀ cage, (2) an amorphous C₆₀-O-C₆₀ complex characterized by the intermolecular distance of 15.04 Å with an oxygen atom forming a bridge between two C₆₀ molecules, and (3) an unidentified crystalline phase with carbonyl bonds.