Bicontinuous Phase in Diblock Copolymer Melts with Added Homopolymer

We compute in the strong-segregation regime the phase diagram of A−B diblock copolymer with added B homopolymer to see if the bicontinuous phase can be stabilized by adding homopolymers. Our work is motivated by the results of Ajdari and Leibler, who showed using a bending expansion that a single copolymer bilayer in excess homopolymer is unstable to Gaussian bends if the copolymers are sufficiently asymmetric. Our methods, which are not limited to a bending expansion, determine the region of homopolymer concentration and copolymer asymmetry for which a bicontinuous phase might be stable.