Flow-induced morphologies of diblock copolymers in a nanotube studied by dissipative particle dynamics simulation

Morphologies of diblock copolymers confined in a cylindrical nanotube under a Poiseuille flow were studies by dissipative particle dynamics simulation. Varying with flow intensity, a symmetric diblock copolymer in a neutral tube exhibits parallel lamellae or stacked disks, stacked bowls, or cylinders; the morphologies in a non-neutral tube are relatively less influenced by flow. An asymmetric diblock copolymer is helical in a neutral tube, but becomes hexagonal under flow; the morphologies in a non-neutral tube are parallel to the tube axis and vary in a less pronounced manner than in a neutral tube. The simulation results reveal that confinement and external flow significantly affect the phase transitions among a variety of morphologies, particularly for copolymers with domains not parallel to the tube axis.