Preparation method of branched polybenzimidazole side chain grafted monovalent / divalent high-selectivity cationic membrane

By introducing branched units and grafted sulfonic acid groups into the polybenzimidazole backbone, a microphase separation structure is constructed, which solves the shortcomings in stability and selectivity of the existing cationic membranes, and achieves high selectivity and high throughput ion separation effects, which are suitable for large-scale water treatment and other applications.

CN120484305APending Publication Date: 2025-08-15UNIV OF SCI & TECH OF CHINA
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Patent Information

Application Number
CN202510077721.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-01-17
Publication Date
2025-08-15

AI Technical Summary

Technical Problem

The existing monovalent selective cationic membranes have shortcomings in terms of stability and selectivity, which is difficult to meet the needs of large-scale water treatment and other applications. In addition, traditional modification methods have problems such as easy loss or peeling of coatings and increased membrane resistance.

Method used

By introducing branched units, grafting sulfonic acid groups and hydrophobic side chains into the polybenzimidazole backbone, a microphase separation structure is constructed, the ion transport channel is optimized, and the differentiated transmission of mono/divalent ions is achieved, and the selectivity and flux are improved.

Benefits of technology

The prepared branched polybenzimidazole side-linked branched cationic membrane significantly improves ion selectivity while maintaining stability and high throughput, simplifies the preparation process, reduces the membrane resistance, and is suitable for large-scale industrial production.

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Abstract

The invention discloses a preparation method of a branched polybenzimidazole side chain grafted monovalent / divalent high-selectivity cationic membrane, which is characterized in that a branched unit is introduced into a main chain to construct a microcavity structure based on the unique tight stacking and rich hydrogen bond network characteristics of polybenzimidazole (PBI), and the pore diameter in the membrane and the free volume of a polymer are regulated and controlled to prepare the branched polybenzimidazole side chain grafted monovalent / divalent high-selectivity cationic membrane. The stable and rapid transmission of monovalent ions is promoted, and a high interception effect on divalent ions is kept. Then molecules containing sulfonic acid groups and hydrophobic side chain molecules are grafted to the branched PBI, the ionic conduction performance is improved, meanwhile, a microphase separation structure can be constructed, the ionic transmembrane energy barrier difference is increased through the ionic hydration energy difference of monovalent and divalent ions, selective transmission of ions is achieved, and the ionic conductivity is improved. Finally, the ion separation membrane with outstanding stability and excellent comprehensive performance of selectivity and flux is obtained.
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