Abstract:

Microphaseseparating behaviors of two typical star-diblock copolymer films have been investigated using the dissipative particle dynamics (DPD) technique. A series of ordered structures and corresponding phase diagrams have been obtained. Results show that, compared to (A_xB_y)₄, the phase diagram of (A_x)₄(B_y)₄ is distinctly symmetric. It is easier to carry out phase-separating for the latter than for the former, similar to their behaviors in bulk. Additionally, it is easier for the island phase to appear in (A_xB_y)₄ films under the same conditions. Some structures formed in bulk and film at the same composition fraction can correspond to each other to a certain extent, and one-dimension confinement can make these systems form more kinds of microphase-separating structures. Besides, both thinner film and stronger A-B repulsion can contribute to enhance the order of relevant structures.

Key words: star-diblock copolymer film; microphase separation; dissipative particle dynamics