Large-Area Uniaxially Oriented Sub-5 nm Line Patterns of Hybrid Liquid Crystals Constructed by Perylene Diimide and Oligo(Dimethylsiloxane)

Abstract

Construction of sub-5 nm long-range ordered structures through self-assembly has received increasing attention. Herein, a series of ODMS-based thermotropic liquid crystals (LCs) containing perylene diimide (PDI) were designed and synthesized. These LCs can form ordered nanostructures with periodic sizes around 5 nm including smectic J (SmJ), oblique columnar (Col_ob ), and hexagonal columnar (Col_h ) phases with change in the volume fraction of ODMS, where the layer spacing of the SmJ phase is less than 5 nm. Thin films with parallel oriented nanolines with line width less than 5 nm can be obtained on PDMS-modified silicon substrates by spin-casting and simple thermal annealing processes. Moreover, owing to the strong π-π interaction between PDI cores, these nanolines are long-range ordered with uniaxial orientation in relatively large areas (1.5×1.5 μm² ) with over 300 continuous microdomains without pre-patterning. These nanostructures provide the possibility of preparing nanotemplates by oxygen plasma etching.

Keywords: long-range order; nanopatterning; oligo(dimethylsiloxane); perylene diimide; sub-5 nm.