Why Does an Electric Field Align Structures in Copolymers?

A microscopic statistical theory of diblock copolymer melts in an electric field is developed within the framework of the random phase approximation. It is found that copolymer melts reveal four different universal types of behavior under an applied field near the spinodal point. The mean-field theory predicts a field-induced shift of both transition temperatures and the spinodal line, the suppression of the body-centered-cubic phase, and the orientational and reorientational phase transitions. New parameters determining the phase behavior have been identified.