Theory of Hierarchical Lamellar Structures from A(B C) n B A Multiblock Copolymers

The phase behavior of A(BC) n BA multiblock copolymer melts is investigated using self-consistent mean-field theory (SCMFT). Solutions of the SCMFT equations corresponding to hierarchical lamellar structures are obtained. The free energy of these structures are used to construct phase diagrams. It is predicted that hierarchical lamellar structures with different number of “internal” BC layers can be formed. The number of BC layers of the stable lamellar structure is determined by the competition between chain entropy and interfacial energy. It is found that more BC layers are preferred when the interactions between A and BC blocks are much stronger than that between B and C blocks.