Bayreuth 1998 – scientific programme

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PO: Polymerphysik

PO 10: Poster: Morphologie und Mechanik

PO 10.6: Poster

Wednesday, March 11, 1998, 15:25–17:15, P1

Effect of High Frequency Oscillatory Shear on Lamellar Polystyrene-Polyisoprene Diblock Copolymers — •H. Leist and U. Wiesner — Max-Planck-Institut f"ur Polymerforschung, Ackermannweg 10, 55128 Mainz

In the present study we focus on the effect of amplitude of high frequency oscillatory shear on the microstructure of a lamellar polystyrene-polyisoprene (PS-b-PI) diblock copolymer. To this end a symmetric PS-b-PI diblock copolymer with low molecular weight is synthesized and TODT determined rheologically. First the known three frequency regimes of orientation [1] under large amplitude oscillatory shear flow in the vicinity of TODT leading to parallel, perpendicular and parallel orientation with increasing frequency are reproduced for this polymer. Orientation experiments under oscillatory shear flow at different shear amplitudes are then performed in the third frequency regime. To detect the orientation behavior after cessation of shear and subsequent quenching to room temperature 2 dimensional small angle X-ray scattering along three orthogonal directions with respect to the deformation geometry is used. Consequences of the results on the orientation diagram of lamellar PS-b-PI under oscillatory shear flow [2] are discussed.
[1] U. Wiesner, Macromol. Chem. Phys., 1997, 198, (3319)
[2] D. Maring, U.Wiesner, Macromolecules 1997, 30, (660)