  Understanding and controlling polyelectrolyte adsorption onto carbon
nanotubes is a fundamen- tal challenge in nanotechology. Polyelectrolytes have
been shown to stabilise nanotube suspensions through adsorbing onto the
nanotube surface, and polyelectrolyte-coated nanotubes are emerging as building
blocks for complex and addressable self-assembly. The conventional wisdom
suggests that polyelectrolyte adsorption onto nanotubes is driven by specific
chemical or van der Waals interac- tions. We develop a simple mean-field model
and show that ion-image attraction is a significant effect for adsorption onto
conducting nanotubes at low salt concentrations. Our theory suggests a simple
strategy to selectively and reversibly functionalize carbon nanotubes based on
their electronic structure which in turn modifies the ion-image attraction.
