Phase Diagram of Rod-Coil Diblock Copolymers: Dissipative Particle Dynamics Simulation

Using dissipative particle dynamics, a refined phase diagram of the rod-coil diblock copolymer is constructed in coordinates copolymer composition-repulsion parameter of different types of units. The diagram describes the microphase separation of copolymer blocks and the orientational ordering of rigid blocks. Simulation of rodlike blocks as rigid bodies makes it possible to reduce computational costs, increase the size of the simulation cell to 32 x 32 x 32 and the total length of the copolymer chain N to 20, to vary the composition of the copolymer chain with a smaller step (up to 0.05), and to investigate the behavior of systems with high degrees of segregation of blocks (up to chi N approximate to 250). Owing to this optimization, the ordering of rigid blocks not only in the lamellar but also in bicontinuous morphology can be observed for the first time. It is also shown that the zigzag and bilayer lamellas described not only in numerical but also in laboratory experiments are metastable and disappear with an increase in the size of the simulated system.