E-mail: yongwang njtech. Two-dimensional covalent organic frameworks COFs are gaining tremendous interest for their potential applications in a diversity of fields. Herein, we present an exfoliation-free and scalable strategy to prepare few-layered CONs based on interface-confined synthesis, in which cheap and recyclable table salt NaCl is used as the sacrificial substrate.
Salt particles are introduced into the reaction system, creating billions of solidβliquid interfaces. Oligomers formed upon the reaction between monomers are immediately adsorbed on salt surfaces, and the following polymerization leading to crystalline CONs is exclusively confined to salt surfaces.
Salts can be easily removed by water washing, producing CONs with the thickness down to a few nanometers and lateral sizes up to hundreds of micrometers depending on the size of salt particles and the concentration of monomers.
Four different kinds of CONs, both imine-linked and boron-containing, are synthesized from this generic method. As a demonstration, we prepare highly permeable and selective membranes using resultant CONs as building blocks.
Thanks to the defect-free stacking of CONs with thin thicknesses and large lateral sizes on porous substrates, the membranes precisely separate similarly sized dyes while allowing ultrafast water permeation.
