Thermal analysis: a unique method to estimate the number of substituents in fullerene derivatives

Without resorting to any spectroscopic and chromatographic methods, the simple thermal analyses techniques like thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been successfully exploited to calculate the number of groups attached per fullerene unit in various fullerene derivatives. The efficiency of these techniques were tested not only with simple derivatives like fullerenol but also with various fullerene core star-like macromolecular systems. These techniques were found to be independent of nature of the groups attached and products formed. The percentage weight loss in TGA has been exploited to calculate the number of addends on fullerene having definite molecular weight (hydroxyl groups and n-butyl acrylate) and enthalpy changes in DSC associated with the dehydroxylation of the unreacted −OH groups have been used as a parameter to calculate the number of addends on fullerene having limited knowledge of molecular weight (polymeric materials like epoxy resins).