Dynamical simulations of rheology and phase behavior of ternary polymer blend systems.

We present the results of a multiscale simulation approach which combines Brownian dynamics simulations with polymer self-consistent field theory to study flow induced phase transitions in microemulsion phases of ternary polymer blends with homopolymers A and B with added copolymer AB. The results match qualitatively with the experimental observations and suggest flow transition of microemulsion phases into a three-phase coexistence followed by macrophase separation at stronger shears. We explore the effect of viscoelastic asymmetry (by varying polymer mobilities) and the copolymer (AB) to homopolymer length ratio ($\alpha )$ on flow induced phase transitions. Though the series of phase transitions remain unchanged, quantitative differences arise as a function of viscoelastic asymmetry and $\alpha $. These transitions are also accompanied by a strong shear-thinning behavior in the rheological response. The results suggest significant differences between ternary polymeric systems and oil-water-surfactant systems. We rationalize the above results from a molecular viewpoint.