Conformations of amphiphilic diblock star copolymers

We study conformations assumed by single diblock star copolymers in a poor solvent by means of the Gaussian variational theory and Monte Carlo simulat ion in continuous space. Cases of stars with internal and external hydropho bic blocks are analysed. While in the former case the collapsed state has a n obvious micellar shape, the latter case exhibits two nontrivial conformat ional structures. Apart from the equilibrium state of a globular hydrophobi c core with hydrophilic daisy loops, one also finds here a metastable state of outstretched hydrophilic blocks with hydrophobic subglobules at their e nds. Such a state appears to be rather long-lived during the kinetics of co llapse of a swollen star. The plots of monomer densities and other observab les computed by means of both techniques are found to be in good agreement with each other.