Stabilization of Individual Carbon Nanotubes in Aqueous Solutions

Single-wall carbon nanotubes pack into crystalline ropes that aggregate into tangled networks due to strong van der Waals attraction. Aggregation acts as an obstacle to most applications, and diminishes the special properties of the individual tubes. We describe a simple procedure for dispersing as-produced nanotubes powder in aqueous solutions of Gum Arabic. In a single step, a stable dispersion of full-length, well separated, individual tubes is formed, apparently due to physical adsorption of the polymer. Single-wall carbon nanotubes (SWNT) are expected to exhibit superior mechanical and electrical properties1-4 as a direct consequence of the nanometric dimensions of the individual tube. Yet, as-produced SWNTs align parallel to each other and pack into crystalline ropes, due to strong intertube van der Waals attraction. Ropes that are typically composed of 100 to 500 tubes pack in a triangular lattice with a lattice constant of a) 1.7 nm.5 The ropes further aggregate into tangled networks. Aggregation was found to act as an obstacle to most applications, diminishing th