Janus MXene nanosheets for macroscopic assemblies

The versatile surface chemistry of MXenes affords a simple way by which the surface of MXene nanosheets can be modified. Here, by selectively grafting polystyrene onto one side of MXene nanosheets, a new amphiphilic surfactant nanomaterial, termed Janus MXene nanosheets (JMNs) or MXene nanosheet surfactants, is designed and synthesized. The prepared JMNs can be dispersed in either water or oil, and can spontaneously assemble at the water-oil interface to reduce the interfacial tension, making a promising solid surfactant to stabilize emulsions. Macroscopic assemblies of JMNs can also be easily prepared by interfacial assembly. Using creamed emulsions as templates, a lightweight, isotropic MXene aerogel is produced in one-step freeze-drying, where the matrix comprises the anchored PS and the pore structure is commensurate with the parent emulsion. Amphiphilic Janus MXene nanosheets are synthesized for the first time by a one-step transferring method, which can act as promising solid surfactants to stabilize emulsions, and assemble into macroscopic 2D ultrathin MXene films and 3D MXene aerogels.