Fabrication of fullerene-decorated carbon nanotubes and their application in flame-retarding polypropylene

Multi-walled carbon nanotubes were decorated with fullerene (C₆₀) via a three-step chemical functionalization, with the goal of combining their unique physical and chemical characteristics and simultaneously improving the solubility of CNTs in organic solvents. C₆₀ molecules, about 0.67% by molecule, were homogeneously bonded onto the surface of the CNTs. Electron microscopy clearly shows that C₆₀ molecules are introduced onto the surface of the CNTs, and this is also evidenced by their UV–VIS absorption spectra. Cone calorimetry measurements showed that compared with pristine CNTs, fullerene-decorated CNTs further reduced the flammability of polypropylene, which may be due to the free-radical-trapping effect of C₆₀ and the barrier effect of the CNT network.