Stabilizing New Morphologies by Blending Homopolymer with Block Copolymer

We examine weakly segregated blends of $\mathrm{AB}$ diblock copolymer and $A$ homopolymer using self-consistent field theory. The addition of homopolymer to a diblock melt is found to stabilize new ordered morphologies: close-packed spheres, hexagonally perforated lamellae, and bicontinuous cubic ( ${\mathrm{Q}}_{\mathrm{Pn}\overline{3}m}$ and ${\mathrm{Q}}_{\mathrm{Ia}\overline{3}d}$) phases. We find highly swollen phases that we associate with spherical, cylindrical, and lamellar micellar regions, and with disordered struts.