Bridge to loop transition in a shear aligned lamellae forming heptablock copolymer

The response to oscillatory shear of a nearly symmetric, lamellae-forming SISISIS heptablock copolymer, is described. The polymer was prepared by sequential anionic polymerization of styrene and isoprene. Transmission electron microscopy (TEM) was employed to provide real-space images of the shear-aligned specimens. The TEM results showed formation of the perpendicular morphology favoring an extended, bridging, chain conformation. The results show that there is an important connection between shear-induced microdomain alignment and molecular conformation in linear block copolymer melts.