Assembly structure and rod orientation of rod-coil diblock copolymer films

The self-assembly and rod orientation of rod-coil (RC) diblock copolymer (DBC) films confined between two identical impenetrable and rod-selective walls was investigated by performing dissipative particle dynamics simulations. Various structures, such as a wetting layer near the surfaces, perpendicular cylinders, parallel cylinders and island-like structures, were observed. Thus a morphological phase diagram as a function of the film thickness and rod length was presented. A long-range rod-rod orientational order was observed in the assembly structures for a rod block above a critical rod length. The critical rod length for the disorder-order transition of the rod orientation was found to be dependent on the assembly structure and film thickness. Our results indicate that the rod length and film thickness influence both the assembly structure and the rod orientation of RC DBCs.