Lyotropic Liquid Crystal Phases as Temples for Selective Interfacial Reactions to Asymmetric Functionalization of 2D Nanomaterials at Large Scale

Anisotropic nanomaterials composed of two halves with different structure, chemistry, or polarity, known as Janus nanomaterials, have distinct properties when compared to symmetrically functionalized analogues. These materials have gained significant attention in many applications such as electronic thin films, drug delivery, sensors, optics, oil/water separation membranes, photoactivated micromotors, photocatalysts, and interfacial modification. Two dimensional (2D) Janus nanosheets are especially intriguing considering their interfacial properties as well as their ability to assemble into higher order and hybrid structures. In this research, we describe an approach to asymmetric functionalization of 2D nanosheets at large-scale through selective interfacial reactions using liquid crystal phases as templates. Several liquid crystal systems composed of surfactants, water and organic solvents were studied by birefringence imaging, cryo-TEM, small-angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) to optimize the microstructures and stability for using as “nanoreactor” templates, and the surfactants included cationic, anionic, non-ionic and zwitterionic types. In comparison to interfacial reaction in a conventional biphasic system, the efficiency of interfacial reaction within the liquid crystal temples can tremendously increase by more than million times (in >10⁶ order), enabling to scale up the synthesis of 2D Janus nanomaterials at industrial scale economically. Several samples of synthesized 2D Janus nanomaterials with different properties for different application have been demonstrated.