Well-defined linear (n = 1, 2) and star (n = 3, 4) architecture [polystyrene-b-poly(dimethylsiloxane)]_n or (PS-b-PDMS)_n block copolymers were synthesized by anionic polymerization and using various chlorosilanes as linking agents. The self-assembly of the novel synthesized copolymers revealed that microphase separation for the star-block copolymers is significantly influenced by entropy constraints due to the increased number of junction points.