Photo-Tunable Supramolecular Ultrathin Surfaces for Simultaneous Homeotropic Anchoring and Superfast Switching of Liquid Crystals

Abstract

Photo-tunable supramolecular ultrathin surfaces functionalized with a soft ultraviolet (UV) treatment of star-shaped reactive amphiphiles are fabricated to simultaneously afford homeotropic anchoring of liquid crystals (LCs) and improve the LC switching performance. Photochemically functionalized ultrathin surfaces are generated by cross-linking star-shaped amphiphilic monomers in the self-assembled monolayers with retention of cluster structure under electric field. Since these star-shaped amphiphiles can construct the close-packed self-organized molecular layer with an alkyl brush at the interface between indium tin oxide and LCs through intermolecular hydrogen bonding, they might make elegant alignment surfaces for the homeotropic anchoring of LCs to provide a new type of vertical alignment layer. It is experimentally revealed that supramolecular ultrathin layers with vertical nanopillars form hydrophobic surface, and afford a stable and uniform homeotropic alignment of LCs even in high-temperature environment. Furthermore, a soft UV irradiation on the self-assembled ultrathin surfaces under electric field yields superfast responsive cross-linked ultrathin surfaces with low power consumption compared to conventional polyimide layer. Notably, this controlled methodology offers advantages of simplicity, low-cost, and scalability in the fabrication of functional alignment surfaces without the need of complex manufacturing steps.