含氟碳侧链阴离子交换膜的聚集态结构调控、交联固定及构效关系研究

Understanding of the relationships between polymeric chemical structure and the morphology of the resultant material is the fundamental, however, indispensable issue in the chemical and materials science area. In this project, circumventing the challenges of anion exchange membrane (AEM), including limited phase-separation, incapability to tailor the condensate structures, as well as non-systematically-established relationships among chemical formulation, nano-/microscopic morphology and macroscopic performance, we aim to introduce superhydrophobic fluorocarbon moieties into the ionomer as side chains, in order to increase the thermodynamic incompatibility between the hydrophilic and hydrophobic phases, thus leading to a well-defined, highly-ordered and stable phase-separated morphology. By systemically tuning chemical formulation, architecture, and the distribution of the fluorocarbon side chains as well as the counterions of functional cation, we will establish the critical factors and means on tuning the morphology and performance of AEM. Eventually, we intend to provide a deeper understanding of fundamental relationships between the chemical architecture of an ionomer and the morphology of the resultant AEM, and between morphology and fuel cell pertinent properties, such as water uptake, ion conductivity and single fuel cell performance. As a long-term goal of this project, we are targeting to provide a scientific guidance for the design and fabrication of functional AEM with tailored performance.

理解聚合物化学结构、聚集态结构与宏观性能之间的关系是化学和材料学科领域一个基础但重要的研究方向。针对现有阴离子交换膜（AEM）存在的相分离程度低、聚集态结构控制困难、且化学结构和聚集态结构关系理解不够全面等问题，该申请课题拟在AEM离聚物中引入超疏水氟碳侧链，提高亲/疏水链段间的热力学不相容性，以诱导薄膜形成高度有序且形貌可控的次级结构，并有效地提高其微/纳相结构的稳定性。通过改变氟碳侧链的结构、含量、分布序列来调控亲/疏水链段间相互作用参数，同时通过改变功能阳离子的抗衡离子和引入可交联功能基团等来考察其对AEM相结构、离子簇尺寸和形貌和膜材料结构稳定性的影响，探索调控AEM聚集态结构的关键因素和手段。在此基础上，全面评价相结构对AEM性能（如吸水率、电导率及单电池性能等）的影响，进一步建立AEM化学结构−聚集态结构−性能之间的关系，为高性能AEM的设计和制备提供理论依据和技术支撑。

构筑具有显著微相分离的相结构是提高阴离子交换膜的离子电导率及其它电化学性能的最有效途径，而理解离聚物的化学结构和相应阴离子膜聚集态结构之间的关系是实现阴离子膜相结构调控的前提和关键。本项目围绕基于聚芳香族主链的阴离子交换膜微相分离结构的构筑、调控及结构-性能关系开展研究，主要取得的代表性进展如下：1）发现少量氟碳侧链的引入可有效诱导聚苯醚、聚(芳基-亚烷基)及聚(芳基-哌啶盐)型阴离子膜形成亲-疏水微相分离结构，并表现出很好的普适性；2）提出了通过抗衡离子调控阴离子膜的聚集态结构，丰富了阴离子交换膜的相结构调控手段；3）讨论了离聚物主链刚性和拓扑结构对阴离子膜聚集态结构的影响，发现高刚性结构的引入和主链支化均不利于亲-疏水相区的聚集，但可以通过引入量的控制实现阴离子膜相结构和尺寸稳定的平衡；4）提出了两种在维持微相分离结构的前提下实现阴离子膜的原位交联策略。该项目的成功实施，揭示了决定阴离子交换膜微相分离结构形成的关键因素、实现了对阴离子膜相结构的精确调控，为阴离子交换膜的高性能化提供普适性的理论依据和技术支撑。