Free Surface-Induced Planar Orientation in Liquid Crystalline Block Copolymer Films: On the Design of Additive Surface Active Polymer Layer

摘要

We recently demonstrated that addition of a surface active polymer (SAP) that segregates on the free (air) surface in liquid crystalline (LC) block copolymer films crucially alters the orientation of the mesogens and microphase separation domains. A block copolymer of poly(butyl methacrylate) (PBMA) combined with an azobenzene LC polymer has been blended as SAP in a polystyrene-based LC block copolymer films possessing similar structure. The present work reveals that the polymer design, the blend ratio, and molecular weight of the surface active polymer significantly affect the orientational alternation for the block copolymer film. The orientational alternation effect by the free surface segregation becomes significantly efficient when SAPs with higher molecular weight is employed.