PHASE-DIAGRAM OF RANDOM COPOLYMERS

A two-letter random copolymer with attraction between similar monomers and repulsion between different ones is investigated using the replica method. This type of interaction favors microphase separation in a compact state of a polymer or in a melt. Frustrations between interactions and polymeric bonds may lead to a freezing transition in a phase where only a few conformations dominate and replica symmetry is broken. Our analysis reveals that stiff polymers have a frozen phase and do not undergo transitions to a phase with a microdomain structure. In flexible polymers, the microphase transition may occur before freezing. Then a new frozen phase with microdomain structure is found and studied. A complete phase diagram is constructed for the two-letter random copolymer.