高稳定性的聚靛红-芳烃碱性膜的可控制备及离子传输机理研究

It is still one of the challenging to improve the chemical stability of anion exchange membrane (AEM) in anion exchange membrane fuel cell (AEMFC). Employing chemically stable polymers and an ordered ion channel of the AEMs can be of great benefit to the AEMFCs. Furthermore, the chemical stability of AEMs is up to a complex interplay of various factors including the chemical structure of the polymers and the microphase structure of the AEMs, and even the synergy of these factors. This proposal is aim to achieve a solid performance of AEMs from the molecular design of polymers and construction of the ordered ion channels of the AEMs. Therefore, the polymer backbone consists of chemical stable C-C bonds and absence of aryl-ether bonds would be benefit to the goal of solid chemical stability of AEMs. So, a linear, soluble, high-molecular-weight and aromatic poly(istain biphenylene) (PIBs) have been synthesized using a super acid-catalyzed polyhydroxyalkylation reaction of isatin and biphenyl compound or other aromatics. For construction of ion channels, photo-cross-linking based on thiol-ene click chemistry have been used to construct 3D cross-linking hydrophilic ion channels. This proposal is focused on polymerizing of different PIB monomers, grafting various ammoniums and the different lengths of dithiol cross-linker, and further investigation the influence of them on the performance of the AEMs. The study is going to find out the mechanism of OH- ion conduction and the microphase structure of AEMs. This study paves the way for mechanically robust ion conducting AEMs with enhanced conductivities and tough chemical stability.

提高碱性离子膜(AEM)的化学稳定性是碱性燃料电池(AEMFC）面临的难题之一。AEM的化学稳定性实质上取决于聚合物离子膜的化学结构以及高级结构等多层次的影响因素以及各影响因素之间的协同作用。本申请基于聚合物离子膜的化学本质，从分子水平设计碱性膜的结构，合成主链全部由稳定的碳-碳键组成的聚靛红-芳烃(PIB)，作为碱性离子膜的聚合物骨架，PIB在常用有机溶剂中易溶解，成膜性好。然后，在PIB分子链限域空间合成交联的亲水分子链，构筑高效离子传输通道，同时提高离子膜的稳定性。高分子量的PIB利用超酸催化方法合成，交联的亲水分子链在PIB分子侧链通过硫醇-烯点击化学反应合成来构筑。通过精准调控PIB单体种类、铵离子的种类以及硫醚结构的链长，研究其对Q-PIBs 碱性膜的化学结构、微相结构和化学稳定性的影响规律，揭示离子传输机制，本研究对丰富和发展碱性离子膜的制备及结构性能关系的理论具有重要意义。

聚合物碱性电解质膜燃料电池(AEMFC) 由于氧还原反应速度快、可使用非贵金属如钴镍等作催化剂，近年来引起国际上极大关注。目前，聚合物碱性离子交换膜(AEM)存在OH-电导率较低、机械性能和化学稳定性较差的关键科学问题，因此急需研发能满足实际应用的碱性离子膜材料。本项目从分子结构设计出发，利用超酸催化傅克聚合反应，高效制备了一系列无醚键的聚合物碱性离子膜。系统研究了阳离子基团种类(季铵离子、哌啶鎓、吗啉鎓)对碱性膜的性能，包括微观形貌、离子传导率、力学性能及化学稳定性等影响。主要研究内容如下：.一 利用超酸催化傅克聚合反应合成了高分子量的聚N-烯丙基靛红-哌啶联苯共聚物以及螺环铵盐聚N-烯丙基靛红-哌啶联苯共聚物，进而制备了光交联型碱性离子膜(Spiro-PIB-co-PAB)。交联型离子膜在80℃时OH-的传导率为33.22-79.28 mS·cm-1，拉伸强度为25.54 -44.73 MPa，高于未交联的离子膜。在80℃，1 M NaOH溶液中浸泡1000 h后交联型离子膜保留了65.2%的OH-传导率，表现了优良的耐碱稳定性。.二 利用超酸催化傅克聚合反应合成了高分子量的聚(靛红-甲基哌啶酮-芳烃)(PIB)，经过侧链功能化反应，制备了一系列碱性离子膜(QAPIB, PyrPIB和PipPIB)。离子膜的IEC 为1.16-1.79 mmol·g-1，80℃时吸水率为42-59%,溶胀度为13.4-20.9%，PipPIB干膜的拉伸强度达到73.09 MPa，断裂伸长率为4.24%。80℃时QAPIB膜具有最高的OH-传导率，达到93.88 mS·cm-1。该类膜在80℃、1 M NaOH中浸泡1050 h，所有膜没有发生破裂，PipPIB膜的OH-离子传导率保留率最高达到71.67%，并对降解机理进行了深入的研究。将QAPIB、PipPIB膜分别制备了膜电极测试燃料电池性能，开路电压分别为1.034 V和1.026 V，接近理论值1.23 V，表明了膜良好的耐气体渗透性。在0.1 MPa背压下，60 ℃时的单电池最高功率密度QAPIB达到1.19 W·cm-2，PipPIB为0.94 W·cm-2。表明本项目制备的碱性离子膜具有优异的电池性能。取得的重要结果：项目执行期内，发表高水平研究论文8篇，其中中科院一区论文3篇，JCR一区论文5篇，申请并授权发明专