The unique mechanical and electronic properties of carbon nanotubes result in their use in many important current and potential applications. Many of these applications rely on the chemical functionalization of the outer surface of the nanotubes to modify their properties. All previous methods involved functionalization of the entire nanotube. Here, we are establishing commercially-scalable procedures to modify segments of the nanotube resulting in what are referred to as block nanotubes. The lack of a large-volume manufacturing technique has prevented the realization of mass production of block nanotubes. We will demonstrate the potential for block nanotubes to be used in various applications such as polymer recycling, oil recovery, and biomass fuel production. Other applications including microelectronics, solar energy and biomaterials could also be impacted. The research project will involve participation of underrepresented groups, primarily Native Americans. A unique blog will be created to document graduate students' experiences working on the project and present a human face of scientists to the broad public. By presenting how the research is carried out from "start-to-finish," the blog is expected to stimulate students into undertaking a career in STEM disciplines.
We plan to synthesize block nanotubes in a commercially-scalable fashion; for example a diblock nanotube would have one fraction of the nanotube with one chemistry and the other fraction with a second chemistry. Two scalable methods to manufacture block nanotubes will be developed. In one case, carbon nanotubes will be used as interfacial stabilizers (e.g. Pickering emulsions) and only those tube parts on the outside of the particles will be functionalized. In the other case, synthesis conditions in a fluidized bed containing flat surfaces impregnated with nanotube growth catalyst will be altered to change the surface chemistry as the tubes grow. Fundamental aspects to be studied in the former include tube length relative to droplet size and tube chemistry prior to modification; for the latter, fundamental aspects include reaction conditions and feed gas composition. Characterizing the spatial variation of nanotube surface chemistry will be performed via transmission electron microscopy and atomic force microscopy. We will test these tubes as interfacial stabilizers in polymer/polymer and oil/water systems, as well as biphasic catalyst supports under higher temperatures and pressures.
