Synthesis, characterization and thermal decomposition behaviour of triphenylphosphine-linked multiwalled carbon nanotubes

Triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNT) were prepared in aprotic media and under anhydrous conditions by treating bromo-arylated-MWCNT with potassium diphenylphosphine (Tpp-MWCNT (1)), or with chlorodiphenylphosphine and butyllithium (Tpp-MWCNT (2)). Tpp-MWCNT were characterised by various techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The presence of the expected elements (C and P) is evident in the XPS spectra. Furthermore XPS results showed the presence of phosphorus with average concentrations of 0.7% and 2.6% in Tpp-MWCNT (1) and Tpp-MWCNT (2), respectively. TGA results revealed the following thermal decomposition order: Tpp-MWCNT (2) < Tpp-MWCNT (1) < purified MWCNT, thus suggesting that the thermal stability of the MWCNT decreases with increasing amount of triphenylphosphine moieties attached to their surface. Moreover TGA results demonstrate that Tpp-MWCNTs have improved flame retardant behaviour since they produce 4–5 times more char than purified MWCNT.