Self-consistent field theory is used to study the phase behavior of melts of semiflexible diblock copolymers. Repulsion between the incompatible blocks leads to microphase separation, while anisotropic external fields and interactions between polymers induce liquid-crystalline phases. Considering symmetric diblocks with quadrupolar interactions, we obtain a nematic-isotropic transition which extends into the lamellar phase and terminates at an internal critical point. For dipolar interactions, ferroelectric nematic and lamellar phases and a novel Lifshitz point are obtained.

• Received 23 February 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.302