Rational design of surface-confined nanostructured self-assemblies based on functional comb-shaped copolymers for tunable molecular orientation

Abstract

Functional ultrathin nanoarchitectures are commonly based on hierarchical molecular self-assemblies that are structurally tunable and facilely fabricable, and have found a broad range of potential applications from nanoelectronics to biosensors. Here, we demonstrate a simple and elegant approach for the rational design of ultrathin molecular nanoarchitectures for tunable interfacial orientation of liquid crystals (LCs) using the surface-confinement of functional amphiphilic copolymers. The surface-confined nanostructured self-assemblies are simply prepared by introducing common functional polymers into amphiphilic systems. The surface-confined copolymeric nanoalignment layer, which is constructed from the simple doping and molecular self-assembly of comb-shaped amphiphilic copolymers in a confined LC medium, comprises a hydrophobic polyacrylate segment with a long side chain moiety capable of uniformly controlling the LC alignment and a hydrophilic polyacrylic acid segment with a carboxylic acid group confined to the hydrophilic surface of indium tin oxide substrate. The combination of structural variations on amphiphilic copolymer system and tunability of molecular orientation makes the surface-confined copolymeric nano-assemblies highly attractive ultrathin nanoarchitectures. The resulting nanostructured self-assemblies exhibit a spontaneous and uniform vertical orientation of LC molecules, simultaneously providing the LC device with a superfast electro-optical switching time and a strong surface anchoring control.