A simulation study on the self-assembly of rod-coil-rod triblock copolymers within nanoslits

Self-assembly of rod-coil-rod R4C12R4 triblock copolymers within a nanoslit is investigated by using dissipative particle dynamics simulations. Perpendicular lamellae (L-perpendicular to) in nonselective or weak selective slits and parallel lamellae (L-parallel to) 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-inverted perpendicular in the interior region, and finally L-parallel to 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.