基于全氟环丁基芳基醚聚合物的碱性阴离子交换膜材料的分子设计及结构与性能关系研究

Alkaline anion exchange membrane (AAEM) fuel cell technology, which can directly convert the chemical energy of hydrogen and oxygen into electrical energy, is of great practical importance for alleviating the issues of energy shortage and environmental pollution in China, due to its advantages such as high efficiency and environmental friendliness. Currently, the development of AAEM fuel cell technology has been seriously hindered by low hydroxide conductivity and insufficient dimensional/chemical stability of AAEM materials. Therefore, the construction of novel AAEM materials with perfluorocyclobutyl aryl ether polymers was proposed in this application. Firstly, the polymer backbones and different quaternized side-chain precursors are designed and synthesized. Then three types of AAEM materials: Comb-shape, Tadpole-like and Dendritic shape, can be prepared by grafting the precursors onto the backbones using Click Chemistry. The polymers will be characterized by NMR and IR, etc. The properties of the polymer membranes such as hydroxide conductivity and dimensional/chemical stability will be investigated, to find out membranes which are promising for AAEM fuel cell application. The morphology of the membranes will be investigated by SEM, TEM and SAXS, and the structure-property relationship of the membranes will be established. This proposal aims to explore how to improve hydroxide conductivity and stability of membranes by designing polymer architectures, which is expected to provide new ideas and theoretical basis for the design and development of high-performance AAEM materials.

碱性阴离子交换膜(AAEM)燃料电池技术能将氢和氧的化学能直接转换成电能，具有高效、环保等优点，对缓解我国能源紧张和环境污染问题具有重要的现实意义。目前AAEM材料氢氧根离子传导率低、尺寸和化学稳定性差的问题已严重阻碍了AAEM燃料电池技术的发展，为此，本申请提出利用全氟环丁基芳基醚聚合物构建新型AAEM材料。首先设计合成聚合物主链和不同的季铵化侧链前体，然后利用点击化学将侧链前体接枝到主链上，分别得到梳型、蝌蚪型和树枝型三类AAEM材料。利用NMR、IR等对上述AAEM材料进行表征。考察膜的氢氧根离子传导率、稳定性等性能，筛选出具有应用前景的膜材料。利用SEM、TEM和SAXS等考察膜的微相分离形态，建立膜的结构与性能之间的关系。探讨如何通过聚合物分子结构的设计来综合提高膜的氢氧根离子传导率、尺寸与耐碱稳定性，以期为高性能AAEM材料的设计与开发提供新思路和理论依据。

碱性阴离子交换膜燃料电池(AEMFCs)是一种新型能源转换技术，能将氢和氧的化学能直接转换成电能，具有安全、高效、环保等优点。因此，开发与利用AEMFCs对缓解我国能源紧张和环境污染问题具有重要的现实意义。目前，碱性阴离子交换膜(AEMs)离子传导率低、尺寸及碱稳定性差的问题已严重阻碍了AEMFCs的发展。为了解决这个问题，我们主要开展了以下工作。设计了含有双季铵盐基团且不含β-氢的侧链前体(QADY)，然后通过Cu(I)催化的叠氮-炔基环加成反应，接枝到聚合物主链，从而合成了一类新型AEMs(DQ-PPO-x-OH)。所得膜具有良好的氢氧根离子导电率，在80°C下，导电率为35.0~63.9 mS/cm。同时，膜在80°C的2 M NaOH中浸泡480小时后，表现出较高的碱性稳定性(导电率保留率>92%)，且核磁共振分析未发现明显降解。DQ-PPO-17-OH膜显示出良好的燃料电池性能，在60°C的H2/O2条件下，峰值功率密度为110 mW/cm。总的来说，这项研究的结果表明，我们的策略在改善AEMs性能方面是有效的。该研究可能为通过加入多个不含β-氢的季铵盐基团来制备高性能AEMs的分子设计提供有价值的思路。在上述工作基础上，我们提出了一种通过引入季铵化树枝基元结构来提高AEMs导电率和尺寸稳定性的新策略。由于引入了季铵化树枝基元，所制备的膜(PPO-QG-x)中形成了清晰的纳米级相分离和良好连通的离子导电通道。PPO-QG-12 AEM(IEC=1.95 mmol/)在20°C时，氢氧根离子导电率可获得高达65.5 mS/m，在80°C时可达121.5 mS/cm，且具有较好的尺寸稳定性。此外，PPO-QG-x AEMs在80°C的2 M NaOH中处理960小时后，表现出良好的碱性稳定性，最大电导率损失为15.1%，且用PPO-QG-12 AEM组装的单电池在60°C下的峰值功率密度为249.4 mW/cm。总的来说，这项工作为实现AEMs的高离子导电率提供了新思路。