Surface modification of multi‐walled carbon nanotubes by perfluoropolyether peroxide

Multi-walled carbon nanotubes (MW-CNTs) were functionalized via covalent linkage of perfluoropolyether (PFPE) radicals obtained by thermal decomposition of linear PFPE peroxide, i.e. a macromolecular compound with a linear structure where (CF2CF2O), (CF2O) and peroxidic units were randomly distributed along the polymer chain. T O(CF2CF2O)m(CF2O)n(O)V T' + CF2O[(CF2CF2O)m (CF2O)n] T + V CF2O The PFPE-functionalized MW-CNTs were characterized by X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), contact angle (CA) and surface area measurements. The effects of the chemical treatment on the conductive properties of MW-CNTs were studied by resistivity measurements at different applied pressures. Moreover, the amount of PFPE chains linked on carbon nanotubes, the PFPE fluids obtained by homocoupling side-reactions and the decomposed portion of PFPE were evaluated by mass balances. After the introduction of PFPE chains on MW-CNTs surface, the water contact angle measured on molded pellets of modified MW-CNTs significantly increased over 150°. This result revealed that the modification of MW-CNTs changed their wettability from a hydrophilic behavior to superhydrophobic, because the low surface energy properties of PFPE have been transferred to the MW-CNTs surface. From conductivity measurements we concluded that the covalent linkage of PFPE chains weakly influenced on electrical properties of conductive MW-CNTs. The experimental results indicated that fucntionalization with PFPE peroxide is a suitable technique to modify and control physical-chemical properties of MW-CNTs.