Abstract:

A comb-shape ether-bond-free polymer backbone containing the carbazole structure, was designed and prepared by superacid-catalyzed polymerization in this article. By adjusting the amount of N-methylpiperidine in the subsequent Menshutkin reaction, polymers with different amount piperidinium ions were obtained. The success of the polymerization and quaternization reaction was proved by ¹H NMR result. Thermal gravity analysis (TG) and dynamic mechanical analysis (DMA) results have showed that the series of membranes have excellent thermal stability and mechanical properties. Electrodialysis (ED) results show that this series of membranes have higher ions flux and separation efficiency than commercial membrane Neosepta ACS. In NaCl/Na₂SO₄ system, the Cl^- flux of QPC-Pip-60 reaches 3.24 mol·m^-2·h^-1, and the permselectivity reaches 11.6. In the NaOH/Na₂WO₄ system, the microphase separation structure makes the OH^- flux up to 3.59 mol·m^-2·h^-1 and the permselectivity up to 70. Long-term stability test in seawater simulated solution and alkali stability test in alkaline solution indicate this ionic membrane has excellent cycle test stability and alkali resistance.

Key words: membrane, ion exchange, selectivity, electrodialysis, super-acid catalyzed polymerization, alkaline stability

摘要：

基于超酸催化聚合机理制备了含咔唑片段的聚合物主链结构，并通过调控季铵化反应中N-甲基哌啶单体的用量，得到了不同哌啶离子含量的阴离子选择性分离膜。通过核磁共振氢谱证明了聚合反应和季铵化反应顺利进行。热重和动态机械分析的测试结果表明膜具有优异的热稳定性和力学性能。通过电渗析 （ED） 测试膜的阴离子分离性能，结果显示离子通量和选择性均优于商业膜Neosepta ACS。在NaCl/Na₂SO₄体系中，QPC-Pip-60的Cl^-通量可达3.24 mol·m^-2·h^-1，选择性可达11.6。在NaOH/Na₂WO₄碱回收体系下，良好的微相分离结构使得OH^-通量可达3.59 mol·m^-2·h^-1，选择性最高为70。长时间稳定性测试和碱稳定性测试结果表明所制备的系列膜具有优异的循环稳定性和耐碱性能。

关键词: 膜, 离子交换, 选择性, 电渗析, 超酸催化聚合, 碱性稳定性