Study of morphology and phase diagram of the H-shaped (AC)B(CA) ternary block copolymers using self-consistent field theory

By using a combinatorial screening method based on the self-consistent field theory (SCFT) for polymer systems, the micro-phase morphologies of the H-shaped (AC)B(CA) ternary block copolymer system are studied in three-dimensional (3D) space. By systematically varying the volume fractions of the components A, B, and C, six triangle phase diagrams of this H-shaped (AC)B(CA) ternary block copolymer system with equal interaction energies among the three components are constructed from the weaker segregation regime to the strong segregation regime, In this study, thirteen 3D micro-phase morphologies for this H-shaped ternary block copolymer system are identified to be stable and seven 3D microphase morphologies are found to be metastable. It is found that in the weaker segregation regime (chi N-AB = chi N-AC = chi N-BC = 45), the minority component can be mixed with other two majority components to form the mixed phase regions, while in the intermediate segregation regime (chi N-AB = chi N-AC = chi N-BC = 60 and 75), the mixed phase regions phase-separate into three distinct phase regions. In the strong segregation regime (chi N-AB = chi N-AC = chi N-BC = 90, 100, and 125), the distinct blocks tend to separate with each other and the phase behavior of this H-shaped (AC)B(CA) ternary block copolymer is similar to that of the three-arm star-like ABC ternary block copolymer. Moreover, the order-disorder transitions and the order-order transitions by varying the interaction parameters are discussed. These results may help in the design of the microstructures of complex block copolymers. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.