Surface characterization and London dispersive surface free energy of functionalized single-walled carbon nanotubes with a blend of polytetrafluoroethylene by inverse gas chromatography

The SWCNTs and SWCNT-polytetrafluoroethylene (PTFE) blend were prepared by using simple reaction mixture in the presence of chromosorb (SiO ₂ ). Surface morphology of SWCNTs and (SWCNT-PTFE) blend was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and surface BET analysis. In addition, the surface thermodynamic properties of n-alkanes and polar probe net retention volumes are measured by inverse gas chromatography (IGC). The London dispersive surface free energy γ _s ^L values were found to be decreased linearly with increase of temperature. The specific component of the surface free energy of adsorption ΔG _a ^S for the polar probes was obtained using the Donnet-Park method. The surface character “S” value (K _b /K _a ) at SWCNTs was found to be 0.74, and SWCNT-PTFE blend surface character value was found to be 0.86. This result demonstrates that the (SWCNT-PTFE) blend surface contains relatively more acidic sites then that of SWCNT surface. Therefore, the IGC results provide useful complementary information on the (SWCNT-PTFE) blend surface.