Morphological transformation and mesostructure formation in diblock copolymer blends

We report the phase structures of a diblock copolymer (BCP) (PS- b-P4VP) blended with bent-core mesogen (BE3-10). High blending concentrations (1:1) resulted in phase separation. However, smaller concentrations resulted in the formation of complexes between the BE3-10 and the BCP. At moderate blending ratio of 1:5, the BCP morphology transformed from a lamellar to hexagonal cylindrical structure and the BE3-10 formed Sm layers that are oriented perpendicular to the BCP interface. At a blending ratio of 1:10, the sample showed remarkable enhancement in the lamellar ordering. In all the blends, the d- spacing was smaller than the original BCP. It is proposed that Sm layer formation and the corresponding chain stretching are responsible for this behavior.