Theory and simulations of mesoscopic morphological transitions

We study the morphological transitions of microphase separated structures in diblock copolymers in the weak segregation regime. A general theory for the stability of the mesophases is presented in terms of the amplitude equation for periodic structures under the single-wave-number approximation. Simulations of morphological transitions in three dimensions are also presented. In particular, we show the time-evolution of domains in the transitions from a rhombohedral structure to a hexagonal structure.