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 distribu tion of lamellar orientation in shear aligned diblocks as a function of str ain amplitude at constant shear duration, frequency, and temperature. At al l strains, predominantly perpendicular alignment is observed with some para llel alignment. Also, there is a small amount of transverse;alignment. This suggests that alignment by shear occurs at the expense of intermediate ali gnments followed by reducing transverse alignment. Increased strain at cons tant time increases the sharpness of the distribution of perpendicular alig nment.