Concentric lamella structures of symmetric diblock copolymers confined in cylindrical nanopores

We applied a real-space self-consistent field theory to investigate the concentric lamella structures of symmetric diblock copolymers confined in the cylindrical nanopores with the preferential surfaces. The symmetric diblock copolymers are selected to locate in the very weak and strong segregation regions where the lamellae obviously exhibit the soft and rigid characteristics, respectively. For the soft lamellae, the cylindrical confinement induces the soft concentric lamella structure with the same thickness as the bulk lamellar period, except that the thickness of the innermost layer depends on the confinement degree. For the rigid lamellae, the cylindrical confinement not only induces the rigid concentric lamella structure having the linear dependence on the confinement degree, but also results in several novel morphologies, such as the connective concentric lamella and the broken concentric lamella structures. The results are quantitatively discussed in a wide range of confinement degree and can be reasonably understood based on symmetry breaking and structural frustration. In addition, our results are quantitatively compared to the available observations from the simulations and experiments, which are in good agreements and may be helpful to experimentally fabricate the ordered nanostructures on the large scale. (C) 2009 Elsevier Ltd. All rights reserved.