Interactions of Carbon Nanotubes with Pyrene-Functionalized Linear-Dendritic Hybrid Polymers

A series of linear-dendritic hybrid polymers, containing pyrene units at the periphery of aliphatic polyester dendrons, were prepared for the purpose of dispersing shortened single-walled carbon nanotubes (SWNTs) in tetrahydrofuran (THF). The prepared hybrids contained 1, 2, 4, 8, or 16 (GO through G4) pyrene units and a linear segment composed of polystyrene. It was found that a minimum of four pyrene units was necessary to form a strong enough interaction with SWNTs to enable steric stabilization in solution, when using a linear polymer segment of 11.5 kDa. Increasing either the number of pyrene units per polymer chain or the length of the polymer segment to 18.0 kDa did not improve nanotube solubility, whereas decreasing the polymer length resulted in significantly less effective nanotube dissolution. The G4 dendron alone, without the linear polystyrene segment, was also found to impart solubility to the nanotubes in THF. Interactions between the series of linear-dendritic hybrids and full-length multiwalled carbon nanotubes were also investigated, and it was found that the polymers exhibited strong interactions with the multiwalled carbon nanotube surface, resulting in the formation of stable solutions. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1016-1028, 2010