Domain patterns in copolymer-homopolymer mixtures

We introduce a dynamical model and carry out computer simulations for phase separation of diblock copolymer-homopolymer mixtures. The homopolymer chains are assumed to be compatible with one of the blocks of the diblock copolymers whereas the two blocks of the diblock copolymer chains are mutually incompatible. In this system, two kinds of phase separation, namely macrophase separation of diblock copolymers and homopolymers and microphase separation in diblock copolymers, take place simultaneously by decreasing temperature. Depending on the strength of the interactions, the domain pattern and its ordering process are changed. We can see both phenomena. One is macrophase separation, which dominates the time evolution of the system; the other is the formation of the mesoscale structure in the whole of the system. We show some typical phase-separated patterns and investigate the kinetics of phase ordering of these patterns by evaluating structure factors. [S1063-651X(98)02711-1].