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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: Interfaces and Thin Films I
CPP 11.2: Talk
Monday, March 31, 2014, 16:45–17:00, ZEU 114
Diblock-copolymer thin films under shear — •Lenin S. Shagolsem1,2, Torsten Kreer1, and Jens-Uwe Sommer1,2 — 1Leibniz Institute of Polymer Research Dresden — 2TU Dresden
By employing molecular dynamics simulations we study the behavior of copolymer thin films under shear. In particular, we consider symmetric diblock-copolymer melts confined by two non-selective walls. Since there is no preferential interaction between the walls and the components of the diblock-copolymer a vertically oriented lamellar structure is formed. We investigate the response of the system to transverse and perpendicular modes of shear and study shear deformation of the lamellae, reorientation transition in transverse shear, and flow behavior. We find that the inclined lamellae state (observed for transverse shear below a critical shear rate) is stabilized by a cyclic motion of chains. Above a critical shear rate, the lamellae orient along the direction of flow. Furthermore, the macroscopic response is investigated by kinetic friction coefficient and shear viscosity. We observe that the critical shear rate, at which the lamellae reorientation occurs, coincides with the onset of shear-thinning.