Self-assembly of rod-coil-rod ABA triblock copolymers in a rod-selective solvent is investigated by using dissipative particle dynamics simulations. The morphologies of the self-assembled aggregates are dependent on the number of copolymers in the aggregate and the rod length of the copolymer. We observe vesicles at short rod block and bowl-like aggregates at slightly longer rod block. In the vesicle region near the phase boundary, metastable bowl-like aggregates can be observed and be transformed into vesicles by annealing process. A transition from the bowl-like structure to the vesicle is observed by increasing the solvophobicity of the mid-coil block. In this study, the difference between the self-assembly of fully flexible ABA triblock copolymer and that of rod-coil-rod triblock copolymer is also discussed.

Dissipative particle dynamics simulations are performed to investigate the self-assembly of rod-coil diblock copolymers R(N(R))C(N-N(R)) within a rod-selective slit. The self-assembled structure of the confined system is sensitively dependent on the rigidity kθ and the fraction fR of the rod block and the slit height H. From the phase diagram of structures with respect to kθ and fR for N = 12 and H = 6, we observe four main structures including disordered cylinder (DC) structure, hexagonally packed cylinders (HPC) perpendicular to the slit surfaces, and lamellar structures parallel (L∥) and perpendicular (L⊥) to surfaces. And structure transitions can be achieved by tuning kθ. The effect of the slit height on the self-assembled structure is also studied for R6C6 and R7C5 copolymers with large kθ. For R6C6, different structures near surfaces and in the interior of slit are observed in relatively wide slits. Whereas for R7C5, L⊥ structure, whose lamellar domain spacing decays exponentially with H, is generally generated. Our results suggest an effective way to control the ordering of rod-coil diblock copolymers under nanoscale confinement.

Self-assembly of rod-coil-rod R4C12R4 triblock copolymers within a nanoslit is investigated by using dissipative particle dynamics simulations. Perpendicular lamellae (L⊥) in nonselective or weak selective slits and parallel lamellae (L∥) in coil-selective slits are observed, and both are almost independent of the slit thickness. However, in the rod-selective slits, the assembled structures are strongly dependent on the slit thickness. With an increase in the slit thickness, we sequentially observe hexagonally packed cylinders (HC) of rod blocks perpendicular to surfaces in thin slits, parallel wavy lamellae, orderly packed alternating cylinders in moderate slits, a mixture structure of HC near surfaces and L⊥ in the interior region, and finally L∥ in wide slits. Our simulation results reveal that the rod block and surface properties play an important role in the assembly of confined rod-coil-rod triblock copolymers. Results also illustrate the competition between the slit thickness and the length scale of lamellae in bulk for the confined copolymers in nanoslits.

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Dissipative particle dynamics simulations are performed to study the self-assembly of rod-coil (RC) diblock copolymers confined in a slit with two coil-selective surfaces. The effect of rod length and slit thickness on the assembly structure is investigated. A morphological phase diagram as a function of slit thickness and rod length is presented. We observe several ordered structures, such as perpendicular cylinders, parallel cylinders, and puck-shaped structure. In the assembly structures, long-range rod-rod orientational order is observed when the rod length exceeds a critical rod length. Our results show that the coil-selective slit influences the assembly structure as well as the rod orientation of RC diblock copolymers.