HYDRODYNAMIC EFFECTS IN 3-DIMENSIONAL MICROPHASE SEPARATION OF BLOCK-COPOLYMERS - DYNAMIC MEAN-FIELD DENSITY-FUNCTIONAL APPROACH

The dynamic mean-field density functional method is used to describe p hase separation including hydrodynamic effects in specific three-dimen sional (3D) compressible copolymer liquids. We show that it is justifi ed to use Darcy's approximation for the velocity field. This simple mo del enables us to reproduce both the increased domain growth and the f aster removal of defects that are a result of hydrodynamics. We perfor m a simulation of a diblock copolymer melt to study the viscous effect s in 3D. The free energy is shown to decrease twice as fast as in a si mulation which only includes diffusion. The hydrodynamics are shown to become important only in the later stages of phase separation as is a lso predicted from theoretical analysis. The separation process procee ds faster because the growth of bulk domains is accelerated compared t o the purely diffusive case. (C) 1998 American Institute of Physics. [ S0021-9606(98)51021-5].