adjacent, which induces transitions into ordered phases of many symmetries, depending on the topology and composition of the polymers. Near the order-disorder transition (weak incompatibility) entropy effects dominate, and the individual polymers retain (within mean field) their Gaussian coil conformation through the transition,[@leibler80; @note], while at much higher incompatibilities the chains are strongly stretched. It is this strongly stretched regime which we address here.

Leibler developed the first complete theory of ordered phases in BCP melts[@leibler80], and predicted the by-now classical phases of lamellar (L), cylindrical (C) and spherical (S) symmetry using the random phase approximation to derive an effective Landau free energy in terms of composition modulations in Fourier space. The strong segregation regime was studied by Helfand and co-workers [@helfand] and Semenov [@semenov85], who predicted the same series of phases with increasing asymmetry, denoted by the fraction $\phi$ of polymer A in an $A\!-\!B$ diblock. (In this work we always use A to denote the minority block). This treatment balances the stretching energy of a polymer chain with the interfacial energy between A and B regions. By assuming an incompressible melt, minimization of the free energy gives a preferred domain size which scales as $N^{2/3}$, where $N$ is 