0 Shear - induced Transitions in Ternary Polymeric System

The first three-dimensional simulation of shear-induced phase transitions in a polymeric system has been performed. The method is based on dynamic density-functional theory. The pathways between a bicontinuous phase with developing gyroid mesostructure and a lamellar/cylinder phase coexistence are investigated for a mixture of flexible triblock ABA-copolymer and solvent under simple steady shear. Various self assembly systems such as lyotropic liquid crystals, surfactants, block copoly-mers can form ordered mesophases (lamellar, cylindrical, spherical, etc). These phases have received much attention because of the fundamental interest to establish universal laws for self-organization phenomena, and also because of the wide range of applications in materials science 1–6. An interesting issue in the design of new materials is modulation of phase behaviour by external and internal factors such as flows 7 , reactions 8 , temperature inhomogeneity 9 , confinements and surfaces 10. In particular, externally applied shear flows are found to lead to macroscale order in block copolymer systems. Moreover, shear introduces a new kind of phase behaviour of block copolymer systems, the so-called orientational phase transitions 11–14. So far, lamellar, hexagonal cylindrical and cubic micellar phases of block copolymers 1