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.