Hydration forces between surfaces of surfactant coated single-walled carbon nanotubes.

The interaction force between functionalized single-walled carbon nanotubes (SWNTs) plays an important role in the fabrication of self-assembled and highly ordered SWNT arrays for a wide range of potential applications. Here, we measured interaction force between SWNTs encapsulated with polymerized surfactant monolayer (p-SWNTs). The balance between the repulsion between p-SWNTs and the osmotic pressure exerted by poly(ethylene glycol) in aqueous solution results in two-dimensional hexagonal arrays of p-SWNTs with very small surface to surface distances (<1 nm). The interaction force measured by the osmotic pressure technique shows characteristic decay length of hydration force in its origin.