Self-assembly of rod-terminally tethered three-armed star-shaped coil block copolymer: Investigation of the presence of the branching in the coil to the self-assembled behavior

Self-assembled behavior of rod-terminally tethered three-armed star-shaped coil block copolymer melts was studied by applying self-consistent-field lattice techniques in three-dimensional (3D) space. Similar to rod-coil diblock copolymers, five morphologies were observed, i.e., lamellar, perforated lamellar, gyroidlike, cylindrical and sphericallike structures, while the distribution of the morphologies in the phase diagram was dramatically changed with respect to that of rod-coil diblock copolymers. The perforated lamella was replaced by the cylinder when f_rod = 0.45, and the lamella was replaced by the perforated lamella when f_rod = 0.5 when the arms A₁ and A₂ had an equal length and the volume fraction of A₃ arm was low enough. Simulations were also performed when the arms A₁ and A₂ had unequal lengths. These results demonstrate that simple branching in the coil induces interesting microphase transitions.