| Horvat, A.; Sevink, G.; Zvelindovsky, A.V.; Krekhov, A.; Tsarkova, L.: Specific Features of dDefect Structure and Dynamics in Cylinder Phase of Block Copolymers , ACS Nano, 2(6), 1143-1152 (2008), doi:10.1021/nn800181m [Link] | |
| Abstract: We present a systematic study of defects in thin films of cylinder-forming block copolymers upon long-term thermal or solvent annealing. In particular, we consider in detail the peculiarities of both classical and specific topological defects, as well as their lateral dynamics. In-situ scanning force microscopy measurements are compared with the simulations based on the dynamic self-consistent mean field theory (DSCFT). We argue that topological arguments and 2D defect representation, sufficient for lamellar systems, do not allow to elucidate the stability and mobility of defects in the cylindrical phase. Here representative defect configurations provide connectivity of the minority phase, and classical disclinations are stabilized by incorporation of alternative, non-bulk structures. In solvent-annealed films with enhanced chain mobility, the neck defects (bridges between parallel cylinders) were observed. This type of non-singular defects has not been identified in block copolymer systems before. The close match between experimental observations and simulation results suggests that the lateral defect motion is diffusion-driven. In addition, 3D simulations demonstrated that the bottom (wetting) layer is only weakly involved into the structure ordering at the free surface. Finally, the morphological evolution is considered with the focus on the motion and interaction of the representative defect configurations. |
Sonderforschungsbereich 481
Komplexe Makromolekül- und Hybridsysteme in inneren und äußeren Feldern
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