Liquid/Liquid Interfacial Synthesis of a Click Nanosheet

A liquid/liquid interfacial synthesis is employed, for the first time, to synthesize a covalent two-dimensional polymer nanosheet. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) between a three-way terminal alkyne and azide at a water/dichloromethane interface generates a 1,2,3-triazole-linked nanosheet. The resultant nanosheet, with a flat and smooth texture, has a maximum domain size of 20 μm and minimum thickness of 5.3 nm. The starting monomers in the organic phase and the copper catalyst in the aqueous phase can only meet at the liquid/liquid interface as a two-dimensional reaction space; this allows them to form the two-dimensional polymer. The robust triazole linkage generated by irreversible covalent-bond formation allows the nanosheet to resist hydrolysis under both acidic and alkaline conditions, and to endure pyrolysis up to more than 300 °C. The coordination ability of the triazolyl group enables the nanosheet to act as a reservoir for metal ions, with an affinity order of Pd²⁺ >Au³⁺ >Cu²⁺ .