环烯烃开环易位交联型聚苯并咪唑质子交换膜的制备及其燃料电池性能研究

Proton conductivity and stability are regarded as two inter-constraint factors in the application of proton exchange membrane fuel cells(PEMFCs). To balance the relationship between these two factors, this project intends to develop a new type of crosslinked sulfonated polybenzimidazole(SPBI) through ring opening cross metathesis (ROCM) reaction. Firstly, a series of sulfonated norbornene derivatives will be synthesized and used as crosslinkers. Then, a crosslinked composite membrane will be constructed through ROCM reaction between the functionalized cycloolefines and the terminal olefin linked on the SPBI polymer. These functionalized crosslinkers can not only form covalently crosslinked network to improve the mechanical and dimensional stability of the membranes but also provide additional proton conducting sites. Through the implementation of this project, a new strategy for preparing crosslinked membranes will be established, and the influence of the structure and content of the crosslinkers behavior on the membrane performance will be studied. In addition, it is promising to develop proton exchange membranes with excellent proton conductivity, high mechanical properties and low swelling degree. All the study mentioned above will contribute to the further development of proton exchange membrane fuel cells.

针对质子交换膜在燃料电池实际应用中质子传导率和稳定性相互制约、两者难以同步提高（Tradeoff效应）难题，提出利用磺化降冰片烯类化合物的开环易位复分解反应构建基于侧链磺酸型聚苯并咪唑（SPBI）的新型交联复合膜体系。拟先设计合成一系结构不同的磺化降冰片烯酰亚胺类化合物，然后将之与含有烯烃的SPBI通过开环易位复分解反应进行复合制备交联型质子交换膜，提高其机械稳定性和尺寸稳定性的同时增加其质子传导能力。通过本项目的实施，可以建立制备功能交联型膜材料的新方法，阐明交联剂结构以及其添加量对膜性能的影响。同时，有望制备出具有优异质子传导能力、高机械性能和低溶胀度的质子交换膜材料，为质子膜燃料电池的进一步发展贡献一份力量。

当前，应用最广泛的阳离子交换膜是以杜邦公司生产的Nafion®为代表的全氟磺酸膜，但是价格昂贵、燃料透过率高、抗氧化性能差等缺点又限制了该膜的应用与发展。基于商业化Nafion®膜存在的问题，本项目拟对阳离子交换膜的高分子链结构进行源头设计，通过高分子链结构及其决定的质子交换膜的微观结构两个层面的协同调控，并通过共混掺杂在离子交换膜内部引入含官能团的无机氧化石墨烯，实现阳离子交换膜材料的质子电导率和化学稳定性的大幅提高，进而实现电池综合性能的提升。研究内容如下：.1.为实现H+在质子交换膜中的传输效率，提高膜的稳定性，设计合成出侧链磺酸型含氟聚苯咪唑，实验结果表明，亲/疏水相分离的微观结构大幅提升了H+的传导与相对选择性。.2.为了进一步提高膜的质子电导率，合成了磺化石墨烯，并利用超声法将之分散在链磺酸型含氟聚苯咪唑中。结果表明，与纯的SPBI相比，共混后的膜具有更高的质子电导率，在共混含量不超过0.5wt%的情况下，共混对膜的机械稳定性和化学稳定性均无明显影响。