Composite separation membrane based on fluorine-containing copolymer and having in-situ grown organic framework structure and preparation method and application of composite separation membrane

Abstract

The invention discloses a composite separation membrane based on a fluorine-containing copolymer and having an in-situ grown organic framework and a preparation method and application of the composite separation membrane. The preparation method comprises the following steps: randomly copolymerizing perfluoro-2,2-dimethyl-1,3-dioxole (PDD), tetrafluoroethylene (TFE) and amine-terminated olefin according to a certain ratio to prepare a fluorine-containing copolymer which can be further subjected to reaction modification; mixing the fluorine-containing copolymer with a PDD-co-TFE binary copolymer according to different ratios to prepare a membrane; and performing Schiff base reaction to grow a covalent organic frame structure sheet layer in situ on the surface of a membrane matrix and introducing a functional group into a frame structure to form a coordination structure so as to obtain the fluorine-containing copolymer composite separation membrane. According to the composite separation membrane prepared by the method disclosed by the invention, binding force between a fluorine-containing copolymer layer and an organic framework structure layer is remarkably enhanced through amino bridging, and the adjustability of an internal pore size is realized through the modification of the internal structure of the pore channel of the organic framework structure layer, so organic gas and inorganic gas (oxygen, carbon dioxide and the like) can be efficiently and selectively separated; and the method has extremely high practical value.

Description

technical field

[0001] The invention belongs to the field of chemical engineering and technology, and in particular relates to a composite separation membrane based on an in-situ growth organic framework structure of a fluorine-containing copolymer, a preparation method and application thereof. Background technique

[0002] Due to its high free volume fraction and good gas permeability, poly(perfluoro-2,2-dimethyl-1,3-dioxole-co-tetrafluoroethylene) (P(PDD- co-TFE)) copolymers have a wide range of applications in the field of gas separation membranes. Poly(perfluoro-2,2-dimethyl-1,3-dioxole-co-tetrafluoroethylene) is currently mainly produced by DuPont Company of the United States, and its trade name is AF, and divided into different grades according to the PDD content and molecular weight of the copolymer, the most commonly used varieties are AF1600 and AF2400. The US patent "US3978030 Fluorinated Dioxin Polymer" disclosed for the first time the method of preparing perfl...

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