  We present a self-consistent field theory (SCFT) study of spherical micelle
formation in a blend of poly(styrene-butadiene) diblocks and homopolystyrene.
The micelle core radii, corona thicknesses and critical micelle concentrations
are calculated as functions of the polymer molecular weights and the
composition of the diblocks. Our results are compared with an earlier scaling
theory and with X-ray scattering data. The agreement between self-consistent
field theory and experiment for the micelle structure is sometimes quantitative
and is generally more successful than scaling theory. For copolymers with
relatively light core blocks, SCFT predictions for the critical micelle
concentration improve over those of scaling theories by an order of magnitude.
In the case of heavier core blocks, SCFT predicts the critical micelle
concentration less well due to inaccuracies in the modelling of the bulk
chemical potential. Overall, we find that SCFT gives a very good description of
spherical micelle formation and hence demonstrate that a mean-field,
equilibrium approach is valid for these systems.
