Micelles of ABC block copolymers with varying degrees of polymerization of the B block (n) and constant lengths of the A and C blocks were investigated by small-angle X-ray scattering (SAXS), analytical ultracentrifugation (AUC), surface tension measurements, and isothermal titration calorimetry. The copolymers consisting of hydrophilic poly(N-acylethylene imine)s, end-capped with a hydrophobic fluorocarbon and a hydrocarbon block, are polymeric surfactants (gamma = 35 mN/m). They form cylindrical micelles with radii of 3.0 nm (n = 35), 3.8 nm (n = 57), and 4.0 nm (n = 72). Their lengths are about 20 run. The micelles can be doped with 1,4-diiodoperfluorobutane for the polymers with n = 57 and 72 but not for n = 35. We assume that the doped micelles form distinct fluorocarbon domains, which are able to incorporate selectively the fluorocarbon dopant. The work presented here is a contribution to the development of multicompartment micelles.