Theory for phase transitions in diblock copolymers: The lamellar case - art. no. 041802

A mean-held type theory is proposed to study order-disorder transitions (OD T's) in block copolymers. The theory applies to both the: weak segregation and the strong segregation regimes. An energy functional is proposed withou t appealing to the random phase approximation (RPA). We find additional ter ms unaccounted for within the RPA. We work out in detail transitions to the lamellar state and compare the method to other existing theories of the OD T and numerical simulations. We find good agreement with recent experimenta l results and predict that the intermediate segregation regime may have mor e than one scaling behavior.