Asymmetric Fullerene Nanosurfactant: Interface Engineering for Automatic Molecular Alignments

Since the molecular self-assembly of nanomaterials is sensitive to their surface properties, the molecular packing structure on the surface is essential to build the desired chemical and physical properties of nanomaterials. Here, a new nanosurfactant is proposed for the automatic construction of macroscopic surface alignment layer for liquid crystal (LC) molecules. An asymmetric nanosurfactant (C₆₀NS) consisted of mesogenic cyanobiphenyl moieties with flexible alkyl chains and a [60]fullerene nanoatom is newly designed and precisely synthesized. The C₆₀NS directly introduced in the anisotropic LC medium is self-assembled into the monolayered protrusions on the surface because of its amphiphilic nature originated by asymmetrically programmed structural motif of LC-favoring moieties and LC-repelling groups. The monolayered protrusions constructed by the phase-separation and self-assembly of asymmetric C₆₀NS nanosurfactant in the anisotropic LC media amplify and transfer the molecular orientational order from surface to bulk, and finally create the automatic vertical molecular alignment on the macroscopic length scale. The asymmetric C₆₀NS nanosurfactant and its self-assembly described herein can offer the direct guideline of interface engineering for the automatic molecular alignments.