二面角构象嵌段型苯并咪唑盐阴离子交换膜的合成与性能研究

为合成耐碱性良好的阴离子交换膜(AEM)，设计具有平面二面角结构的三联苯苯并咪唑环单体，进而合成具有空间位阻保护的聚三联苯苯并咪唑盐AEM。苯并咪唑环和三联苯形成具有一定角度的平面二面角，同时利用三联苯的空间位阻作用，阻止氢氧根离子对苯并咪唑环的攻击，增强膜的耐碱性。通过表征分析膜的微观结构、溶胀性能、离子电导率、耐碱性等数据，明晰平面二面角和三联苯的空间位阻效应对膜性能的影响。同时利用密度泛函理论计算验证三联苯结构对改善苯并咪唑环耐碱性的贡献。调控反应条件与合成步骤，使膜中形成良好的微相分离结构及适当的纳米孔道，促进提高膜的离子电导率。采用软刻蚀法把催化剂涂覆于AEM制备膜电极，可使催化剂层具有一定的结构或模式，以利于改善电池运行过程的水的管理与调配，进而提高单电池性能。通过该结构的设计与调控，有望解决AEM耐碱性不足的科学问题，为碱性燃料电池的大规模商业化应用提供借鉴。

A benzimidazole ring with a planar dihedral structure is designed and then is used to synthesize benzimidazole ring polymer with steric protection. The polymer is further used for preparing anion exchange membranes(AEMs) with good alkaline stability. The benzimidazole ring and meta-terphenyl can form a planar dihedral angle, and the steric hindrance of meta-terphenyl is used to prevent the benzimidazole ring from the attack of hydroxyl ion to reduce the ring degradation. This structure is efficient at maintaining the ionic conductivity. The influences of the planar dihedral angle and steric resistance of meta-terphenyl on the membrane property are elucidated by characterizing the microstructure, swelling, ionic conductivity and alkaline stability. Density functional theory is also used to study the effect of meta-terphenyl on the alkaline stability. The ionic conductivity can be improved by the formation of microphase separation and nanopores in the AEMs. The soft lithographic technique, previously demonstrated for use in the preparation of patterned thin films, is adopted to produce patterned catalyst layers on the AEM for single cells with features having a thickness of up to 20 μm. The resulting catalyst layers contained precise microscopic patterns (containing arrays of microscale cylindrical holes) that could be tuned for improving the performance of single cells. This structure can solve the problem of poor alkaline stability of AEMs. The research is expected to provide guidance for the application of alkaline fuel cells.