  The formation of various bicontinuous phases from binary blends of linear AB
diblock copolymers (DBCPs) is studied using the polymeric self-consistent field
theory. The theoretical study predicts that the double-diamond and the
"plumber's nightmare" phases, which are metastable for neat diblock copolymers,
could be stabilized in block copolymers with designed dispersity, namely,
binary blends composed of a gyroid-forming DBCP and a homopolymer-like DBCP.
The spatial distribution of different monomers reveals that these two types of
DBCPs are segregated such that the homopolymer-like component is localized at
the nodes to relieve the packing frustration. Simultaneously, the presence of a
local segregation of the two DBCPs on the AB interface regulates the
interfacial curvature. These two mechanisms could act in tandem for
homopolymer-like diblock copolymers with proper compositions, resulting in
larger stability regions for the novel bicontinuous phases.
