Role of Strain in Controlling the Orientation Distribution in Oscillatory Shear of Diblock Copolymers as Studied by SAXS

Small-angle X-ray scattering is used to examine quantitatively the distribution of lamellar orientation in shear aligned diblocks as a function of strain amplitude at constant shear duration, frequency, and temperature. At all strains, predominantly perpendicular alignment is observed with some parallel alignment. Also, there is a small amount of transverse alignment. This suggests that alignment by shear occurs at the expense of iIntermediate alignments followed by reducing transverse alignment. Increased strain at constant time increases the sharpness of the distribution of perpendicular alignment