The effect of pyrene distribution within pyrene-functionalized random and block copolymers on noncovalent polymer/single-walled carbon nanotube (SWNT) interactions was investigated. The block copolymers served as superior solubilizing agents in comparison with the random copolymers. Also, increasing the pyrene content within a polymer, while a constant molecular weight was maintained, improved SWNT solubility and therefore had to result in stronger polymer-nanotube interactions. However, increasing the length of the pyrene-containing block diminished nanotube solubility, likely because of a lower number of polymer chains that were capable of binding to the nanotube surface. Atomic force microscopy and transmission electron microscopy indicated that the polymer-SWNT interactions were capable of partially debundling the nanotubes into individual solvated structures. (c) 2006 Wiley Periodicals, Inc.