Biaxial alignment of block copolymer-complex lamellae

Abstract

Microphase-separated lamellar block copolymers can be oriented perpendicular to a substrate. The application of this attractive configuration as a template for nanostructure fabrication requires additionally long-range in-plane alignment of the lamella, for which no simple procedures are available. Here we present a convenient solution to this problem by exploiting the combination of supramolecular liquid-crystalline ordering of the block copolymer in combination with PTFE rubbing technology. The mesogenic ligands incorporated in one of the blocks interact with the substrate and control the self-assembly, rendering a vertical orientation of the microdomains. In addition the vertical lamellae orient parallel to the friction-deposited PTFE layer leading to long-range lateral ordering, providing unique new possibilities for block copolymer nanotechnology.