分子链含POSS磺化聚酰亚胺质子交换膜的制备与性能研究

Introducing of the polyhedral oligosilsesquioxane (POSS) in sulfonated aromatic polymer to fabricate hybrid proton exchange membranes (PEMs) could effectively improve proton conductivity, reduce hydrolyzation and methanol permeability in fuel cell applications. However, these classic hybrid membranes have poor mechanical properties, limited POSS content and complicated preparation process. In this program, a series of octaphenyl POSS diamines was designed and introduced in polyimide chain, and the corresponding PEMs would be prepared. The goal of this program is introducing the POSS in sulfonated polyimides with covalent bond, in which a more uniform and stable microphase organic-inorganic separation structure with more smooth proton conductive path could be formed to overcome the drawbacks of the state-of-the-art sulfonated polyimides such as poor hydrolyze stability and mechanical properties at high sulfonation degree for fuel cell applications. On the basis of key research on the micro-structure of sulfonated polyimides containing POSS membranes, the relationship between organic-inorganic interfacial structure and the membrane properties in fuel cell will be clarified. Further more, the process of membrane preparation in this program also could be simplified compared to the classic organic-inorganic hybrid membranes. The accomplishment of this program would give a meaningful direction for fabrication of POSS-sulfonated aromatic hybrid polymers as PEMs.

以笼型倍半硅氧烷（POSS）掺杂芳香类磺化高分子形成的有机-无机杂化膜材料有效地提高了芳香类磺化高分子质子交换膜的质子传导率、耐水解性能、阻醇性能和稳定性，但该材料存在POSS掺杂量有限、机械性能差、制备过程复杂等问题。本项目提出以二胺功能化的八苯基笼型倍半硅氧烷为出发点，制备分子链含POSS磺化聚酰亚胺质子交换膜，将八苯基笼型倍半硅氧烷以共价键形式直接引入磺化聚酰亚胺高分子链，使POSS更稳定、更均匀地分散于高分子膜，形成有机-无机微相分离结构，为质子提供顺畅的传递通道，解决传统磺化聚酰亚胺易水解、应用条件下机械性能差等问题，简化传统掺杂制膜步骤。重点研究POSS以共价键引入磺化聚酰亚胺对质子交换膜微结构的影响，阐明该膜有机-无机微结构对燃料电池质子交换性能的促进作用。研究结果将为POSS-磺化芳香类聚合物质子交换膜的制备提供新思路。

本项目以二功能、单功能以及多功能化的笼型倍半硅氧烷（POSS）为出发点，分别制备了主链含POSS型、侧链含磺化POSS型、POSS交联型以及侧链含POSS交联型四个系列的质子交换膜，将笼型倍半硅氧烷以共价键形式成功引入高分子链。结果表明，相比于传统POSS掺杂材料，采用共价键引入POSS的方法使POSS更稳定、更均匀地分散于高分子膜。并且，由于Si-O键和水合质子的相互作用，POSS诱导了磺酸基团的聚集，形成了连续的质子传递通道，提高了质子传导率。解决了传统芳香类聚合物质子交换膜易水解、应用条件下机械性能差等问题；解决了传统POSS掺杂制备聚合物薄膜时POSS掺杂量有限、机械性能差、制备过程复杂等问题。所得四个系列质子交换膜中，侧链含POSS交联型质子交换膜在保证高的质子传导率的同时，具有优异的机械性能和稳定性。该项目为POSS掺杂聚合物质子交换膜的制备提供了新思路。. 另外，基于本课题组具有在吡啶、二氮芴基化合物的合成基础，针对传统磺化芳香型聚合物质子交换膜机械性能差、稳定性不佳以及甲醇透过率高的缺点，本课题组将吡啶、二氮芴结构引入磺化聚醚醚酮质子交换膜，形成离子交联结构，所得材料在保证可应用质子传导率的同时，具有优异的机械性能、化学稳定性以及低的甲醇透过率。同时，考察了该类含吡啶聚合物的热性能、机械性能及相关离子识别性能。研究表明，含二氮芴基聚合物材料在保证优异的耐热性能和机械性能的同时，具有良好的溶解性和可加工性能。部分含二氮芴、二吡啶吩嗪基聚合物具有优异的离子识别性能。