Our work in immiscible polymer blends has three parts. First, we have shown that it is possible to control which phase of an immiscible polymer blend a nanotube resides in by altering the surface chemistry of the nanotube. Second, we have shown that if a nanotube resides in the minor phase of an immiscible polymer blend, it is protected from breakage during mixing in a conical laboratory twin-screw extruder. In fact, even if the nanotube resides in the major phase, breakage is reduced. Third, we will present some preliminary results on the use of block nanotubes, that is a single nanotube having one block with one chemistry and another block with a second chemistry, on the modification of polymer blends.