The synthesis of a second generation of end of nanofluids based on carbon nanotubes

In traditional modified methods, the functionalized nanoparticles appear and behave like solids in the absence of solvents. In this paper, a new family of modified nanoparticles, which exhibit liquid-like behavior in the absence of solvents at room temperature, is prepared. The amine-functionalized multi-wall carbon nanotubes (MWNTs) derivative is obtained in a two-step process comprising of oxidation of the tubes with strong acid and then neutralization reaction and hydrogen bonding followed by a surface reaction with dipoly(ethylene glycol) octadecyl amine. The sample is investigated by Fourier transform-infrared spectrometer analysis (FTTR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and rheological analysis. As a result, the carboxyl and hydroxyl groups were found on the surface of MWNTs, when MWNTs were modified by strong acid. Dipoly (ethylene glycol) octadecyl amine is 40 wt% corresponding to the dense surface coverage of one modifying molecule per 50 carbon atoms of MWNTs. The material is a viscous liquid at room temperature with lower versatility and it can be dispersed in various solvents due to amphiphilic properties of the modifier molecule. Their dispersion, high thermal stability, low vapor pressure and ability to flow at low temperatures make them attractive as lubricants, plasticizers, or film-forming precursors.