A new, non-wrapping approach to functionalizing nanotubes, such as carbon nanotubes, in organic and inorganic solvents is provided. In accordance with certain embodiments, carbon nanotube surfaces are functionalized in a non-wrapping fashion by functional conjugated polymers that include functional groups. Various embodiments provide polymers that noncovalently bond with carbon nanotubes in a non-wrapping fashion. For example, various embodiments of polymers are provided that comprise a relatively rigid backbone that is suitable for noncovalently bonding with a carbon nanotube substantially along the nanotube's length, as opposed to about its diameter. In preferred polymers, the major interaction between the polymer backbone and the nanotube surface is parallel .pi.-stacking. In certain implementations, the polymers further comprise at least one functional extension from the backbone that are any of various desired functional groups for functionalizing a carbon nanotube.