机械互锁型离聚物的分子设计合成与构效关系研究

Highly efficient and highly selective membrane technologies are extremely attractive and challenging for energy conversion and utilization, for which the molecular design of ionomers is the core. So far, the ion conductivity of most membranes is not sufficiently high even with the optimized ion exchange capacity (IEC) and hydration number, primarily because of the restricted hopping of counter-ions within the hydrophilic channels of membranes. To address this limiting issue, in this proposal, the mechanical bond will be designed to replace the conventional covalent bond to link the ionic groups and polymer backbone, so that the ionic groups can dynamically rotate or slide along the polymer thread, leading to the reduction of activation energy for the transport of the counter-ions. Specifically, a series of ionic cyclophanes and the corresponding molecular threads (either small molecules or macromolecules) will be synthesized firstly, and then the mechanical bond will be explicitly built from these two components by the aid of various intermolecular forces such as π-π stacking, charge transfer, radical cation interaction, and hydrogen bonding. The synthesis protocol, water affinity, film-forming capability, chemical stability, mechanical property, and ion conductivity of these mechanically interlocked ionomers will be thoroughly investigated, with the emphasis on the effect of the mechanical bond on the microscopic phase-separation behavior, hydration behavior, and ion migration behavior of the resulting membranes. The relationship between the ionomer structure and property will be systematically studied to elucidate the working principle of the mechanical bond. It is anticipated that this study will provide a solid experimental and theoretical foundation for the development of highly conductive ion exchange membranes for next-generation electrochemical devices.

面向能源转化利用的高效高选择性膜分离技术是极具吸引力和挑战性的研究课题，其核心是离聚物的分子设计合成。针对现有离聚物体系在最佳离子交换容量和水合数条件下的离子传导率仍是制约其发展的瓶颈问题，基于膜微观亲水通道中的离子跳跃传输机理，本项目拟通过构筑机械互锁型离聚物来取代传统纯共价型离聚物，让离子官能团可以沿聚合物轴转动和滑动，从而降低离子跳跃传输活化能。为此，拟设计合成系列离子型环番化合物和可与之形成穿插型复合物的分子轴，然后利用π-π堆积、电荷转移、自由基阳离子相互作用、氢键等分子间力构筑机械互锁键；研究机械互锁型离聚物的合成方法、亲水性、成膜性、化学稳定性、机械强度和离子传导率；重点考察机械互锁键对离聚物的微观相分离行为、离子官能团的水合行为和离子传输行为等的影响，探讨它们之间的内在联系，总结其结构调控规律，并解释其作用机理，为离子交换膜及其器件的跨越式发展提供理论和实验依据。

面向能源转化利用的高效高选择性膜分离技术是极具吸引力和挑战性的研究课题，其核心是离聚物的分子设计合成。针对现有离聚物体系在最佳离子交换容量和水合数条件下的离子传导率仍是制约其发展的瓶颈问题，基于膜微观亲水通道中的离子跳跃传输机理，本项目开发了一系列基于柱[5]芳烃、百草枯、环状聚芳醚等功能环番，设计了一系列基于给体-受体、自由基阳离子、氢键等分子间作用力的小分子轴和高分子轴，采用直接聚合法和穿线封端法制备了一系列具有大离子簇结构的磺酸型和磷酸型质子交换膜以及季铵盐型和吡啶型阴离子交换膜，以离聚物的化学结构调控膜的离子通道，系统研究了膜的离子传导率、离子传输活化能、吸水率、溶胀率、微观相态结构、氧化稳定性、热稳定性、机械强度、离子选择性等，评价了膜在全钒液流电池中的性能，建立了膜的化学结构-理化性能-电池性能之间的关系，为离子交换膜及其器件的跨越式发展奠定坚实的理论和实验基础。