Method for preparing high-crystallinity covalent organic framework film by using ionic liquid-water interface

Abstract

The invention discloses a method for preparing a high-crystallinity covalent organic framework membrane by using an ionic liquid-water interface. The method comprises the following steps of: dissolving an aldehyde monomer in a hydrophobic ionic liquid to obtain a solution A; dissolving an amine monomer and an acid catalyst p-toluenesulfonic acid in deionized water to obtain a solution B; transferring the solution A into a reactor, adding deionized water to the surface of the solution A, layering, adding the solution B to the upper part of the deionized water layer, and performing a reaction for more than 3 days in the reactor under the condition of still standing at room temperature, so as tosynthesize the covalent organic framework membrane by using a double-diffusion control mechanism that the hydrogen-bond interaction of the acid catalyst and the amine monomer and the high viscosity of hydrophobic ionic liquid are utilized and the diffusion rates of the two monomers are limited at the same time. The covalent organic framework membrane prepared by the method has very high crystallinity, the specific surface area of themembrane is increased by 4 times compared with that of a covalent organic framework membrane synthesized on a traditional dichloromethane-water interface, and the solvent flux is also increased by 2 times under the condition that dye interception is not influenced.

Description

technical field [0001] The invention belongs to the technical field of preparation of covalent organic framework membranes, and in particular relates to a method for preparing covalent organic framework membranes with high crystallinity by using an ionic liquid-water interface. Background technique [0002] Covalent organic frameworks are crystallites with advantages such as low density, permanent porosity, and high specific surface area. Unlike conventional polymers and ceramics with inhomogeneous pore sizes, covalent organic frameworks usually have uniform pore sizes, and their pore sizes can be well controlled and tuned by pre-design or post-modification of monomers. However, covalent organic frameworks are powdery crystallites, which cannot be dissolved and processed, which seriously affects their wide application. [0003] In recent years, researchers have proposed several preparation methods of covalent organic framework membranes, mainly including interface (air-liqu...

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Problems solved by technology

However, there are two problems with this method: first, because the organic solvents that form the two-phase interface are usually highly toxic and volatile, this method will cause environmental pollution, and the volatilization of the solvent often causes interface disturbances, which will also affect the common phase. Second, when using liquid-liquid interface to synthesize covalent organic framework film, the rate of polymerization reaction can only be controlled by the action of catalyst and amine monomer, so that high crystallinity cannot be obtained. Covalent organic framework membranes, which have affected the practical application of covalent organic framework membranes to a certain extent

Research on this aspect has not yet been reported in the literature

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