Nitrogen-containing branched polymer, anion exchange membrane, and method for preparing anion exchange resin

A method for preparing an anion exchange resin, wherein the anion exchange resin comprises a nitrogen-containing branched polymer;

• a molecular structure of the nitrogen-containing branched polymer comprises a nitrogen-containing heterocycle, a branched structure, and an aryl group, the number of branching site of the branched structure is not less than 3, and the aryl group is connected to the branching site of the branched structure through the nitrogen-containing heterocycle;
• the aryl group and the branched structure satisfy a relationship:
• A:B=80-99:1-20, wherein A represents a molar proportion of the aryl group in the nitrogen-containing branched polymer, and B represents a molar proportion of the branched structure in the nitrogen-containing branched polymer;
• a polydispersity index of the nitrogen-containing branched polymer is not greater than 2.6, and a weight-average molecular weight of the nitrogen-containing branched polymer is in a range of 40,000 g/mol-500,000 g/mol;
• the method for preparing an anion exchange resin comprises:
• S1. preparing a reaction monomer mixture containing a monomer I, a monomer II, and a monomer III, and adding an acid catalyst to the reaction monomer mixture under a temperature of −5° C.-0° C. to obtain a reaction solution;
• wherein the monomer I is an aryl monomer, the monomer II is a monomer containing the branched structure, and the monomer III is a monomer containing the nitrogen-containing heterocycle;
• S2. subjecting the reaction solution to an oligomerization reaction to produce an oligomer mixture, wherein a reaction temperature of the oligomerization reaction is 0° C.-10° C.;
• S3. subjecting the oligomer mixture to a high-polymerization reaction, wherein a reaction temperature of the high-polymerization reaction is 0° C.-24° C.;
• S4. separating a polymer from a product of the high-polymerization reaction, and performing an acid-removal treatment on the polymer to obtain the nitrogen-containing branched polymer;
• and
• S5. preparing a quaternization reaction solution by adding the nitrogen-containing branched polymer and a quaternization reagent to a solvent B for a quaternization reaction, and separating the anion exchange resin from a product of the quaternization reaction.