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 (SiO₂). 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 values were found to be decreased linearly with increase of temperature. The specific component of the surface free energy of adsorption 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.