Noncovalent Engineering of Carbon Nanotube Surfaces
J. Chen, R. Ramasubramaniam and H. Liu
Zyvex Corporation, US
Keywords: nanotube, nanotechnology, functionalization, composite, solubilization
Single-walled carbon nanotubes (SWNTs), due to their novel structural, thermal, electrical, mechanical and optical properties, are expected to find applications in many fields. Pristine SWNTs are generally insoluble in common solvents, and difficult to functionalize controllably. We recently reported a non-wrapping approach to noncovalent engineering of carbon nanotube surfaces by short, rigid functional conjugated polymers, poly(aryleneethynylene)s (PPE). This method enables the superior control of the relative placement of functionalities on the nanotube surface while still preserving nearly all of the nanotube's intrinsic properties. We report here that the PPE-functionalized SWNTs can be solubilized in various organic solvents and water, and the solubilities are as high as 10 mg/ml. The soluble SWNTs with specific functionalities can be used as novel gelators that can gelate various organic solvents. In contrast to pristine SWNTs, soluble SWNTs can be homogeneously dispersed in commercial polymers such as polycarbonate, polystyrene etc. These composites showed dramatic improvements in the electrical conductivity with extremely low percolation threshold ~0.05-0.1 wt% of SWNT loading. The resulting polymer composites also show significant enhancement in mechanical strength. The mechanical measurement showed that 2 wt % of soluble SWNT filling resulted in a 79% increase in the tensile strength of polycarbonate.
Nanotech 2004 Conference Technical Program Abstract