ABSTRACT
We report the synthesis of graphenes with tunable properties due to the growth of needlelike iron oxide (IO) nanoparticles on their surfaces. The electrical conductivity, flexibility, and magnetic properties of graphene nanosheets (GNSs) could be tuned on demand by fine controlling both the surface coverage and the length of the IO nanoneedles. The degree of coverage of the IO nanoparticles on the surface of the GNSs made it possible to control the resulting properties of the IO/GNSs on demand. As examples of their utility, paperlike materials were generated by simple filtration, and the resulting IO/GNS nanocomposites showed extraordinary removal capacity and fast adsorption rates for As(V) and Cr(VI) ions in water. Another possible application is the preparation of multifunctional films equipped with conductivity, flexibility, and magnetic properties. The fabrication process is easy to scale up at a low cost. In addition, both the colloidal solution and film forms of the resulting IO/GNSs were effective for removal of heavy metal ions, meaning this material could be utilized for actual industrial applications.
ABSTRACT
The electrical conductivity of surface-modified multiwalled carbon nanotubes (MWNTs)/poly-phenylenesulfide (PPS) composites prepared by melt processing is measured as a function of frequency with the MWNTs content and evaluated in terms of percolation behavior. The imidazoledithiocarboyxlic acid (imidazole) is grafted from the oxidized MWNTs, and the results of surface analysis, HRTEM and thermal analysis reveal that the MWNTs are successfully modified by imidazole. Although the imidazole-modified MWNTs are most damaged during the modification reaction of imidazole with carboxylic group onto the MWNTs as well as during the oxidation, so that the modified MWNTs are significantly shortened, the imidazole modification of MWNTs enables the PPS composites to have the lower percolation threshold and the higher electrical conductivity than the oxidized MWNTs/PPS composites. It is recognized that the better dispersion of MWNTs derived from the compatibility of PPS with sulfur moiety in the imidazole and the presence of N-H groups which may act as an assistor of the electronic conduction and/or decrease the energy barrier required for the charge carriers to hop from conducting clusters to neighbors contribute to the enhancement of the electrical properties of the imidazole-modified MWNTs/PPS composites.
