Amphiphilic poly(2-alkyl-2-oxazoline) diblock copolymers of 2-methyl-2-oxazoline (MOx) building the hydrophilic block and either 2-nonyl-2-oxazoline (NOx) for the hydrophobic or 2-(1H,1H',2H,2H'-perfluorohexyl)-2-oxazoline (FOx) for the fluorophilic block were synthesized by sequential living cationic polymerization. The polymer amphiphiles form core/shell micelles in aqueous solution as evidenced using small-angle neutron scattering (SANS). Whereas the diblock copolymer micelles with a hydrophobic NOx_n block are spherical, the micelles with the fluorophilic FOxn are slightly elongated, as observed by SANS and TEM. In water, the micelles with fluorophilic and lipophilic cores do not mix, but coexist.