结晶型磺化聚醚酮质子交换膜材料的分子设计及性能研究

The objective of this project is to design sulfonated poly(ether ketone)s (SPEKs) as high performance proton exchange membranes (PEMs). This project aims at overcoming technical barriers that traditional PEMs suffer from poor dimensional stability and methanol resistance. Here we present the molecular design and detailed synthesis procedure of SPEKs with a certain degree of crystallinity, which is in contrast with former amorphous SPEKs. The SPEKs consist of poly(ether ketone) (PEK) backbone and clustered sulfonated phenyls as functional units, linear SPEKs with sulfonated side-chain or main chain are synthesized depending on the joint mode of functional units and backbone. Through inducing crystallization within the PEK moiety of PEM, the dimensional stability, methanol permeability and mechanical property are significantly enhanced. The proton conductivity of PEM is improved by increased efficiency of sulfonic acid groups which brought up by clustered sulfonated phenyls in SPEKs. This research project attempt to reveal: (1) structure-property relationship of SPEKs; (2) the correlation of crystallinity and property of SPEKs; (3) the relationship among hydrophobic phase, hydrophilic phase and crystalline phase in morphology；（4）some features of SPEKs as PEM in DMFC application.

本项目拟制备具有结晶行为的磺化聚醚酮质子交换膜，力图从聚合物结晶角度突破传统磺化聚芳醚质子交换膜尺寸稳定性差、阻醇性能差等科学难题。从构思上，本项目突破了传统磺化聚芳醚酮质子交换膜材料非晶形态的概念，有据可依的给出了结晶性磺化聚芳醚酮质子交换膜的分子设计思路及具体制备过程。以结晶性聚醚酮链段为分子主体，局部高密度磺化苯环为功能性基元，设计了侧链磺化结晶聚醚酮，主链磺化结晶聚醚酮分子结构及制备路线。聚醚酮链段的结晶行为，有利于稳固材料的疏水相，提高材料的尺寸稳定性，耐甲醇性能及机械性能；高磺化密度的多苯环基元，提高磺酸基团的有效利用率，改善材料的质子传导性能。研究此类材料分子结构对性能的影响；分析结晶的成因条件及其对材料性能的贡献；探究此类薄膜亲水相、疏水相、结晶相的三者的微观结构及其相互影响的科学规律；得出结晶性磺化聚醚酮材料作为直接甲醇燃料电池电解质膜的性能特点。

本项目圆满的完成了任务书的规定工作，制备了具有结晶行为的磺化聚醚酮质子交换膜。利用传统的高温聚合方法，制备了侧链具有密集磺化结构的半结晶型磺化聚醚酮质子交换膜。与结构相似的无定型磺化聚芳醚质子交换膜相比，半结晶的膜材料具有优秀的尺寸稳定性和阻醇性能。采用新的聚合方法，引入新型单体N-苯基(4,4'-二氟二苯基)酮亚胺参与亲核缩聚反应，通过一步的磺化-水解过程，得到了一系列主链型半结晶的磺化聚醚酮质子交换膜。探究了密集磺化的亲水微嵌段对薄膜微观相形貌的影响，研究了微观相形貌和宏观性能之间的关系。为了进一步降低亲水链段对聚醚酮疏水主链的影响，引入了尺寸更大的密集磺化侧链，降低了亲水链段的比例，进一步提升了疏水链段的规整度，实现了更高的结晶度，使薄膜获得优秀的尺寸稳定性和阻醇性能。与此同时，在密集磺化亲水侧链和结晶的聚醚酮主链之间引入柔性链段，进一步改善了薄膜的亲水/疏水相分离形貌，提升了质子传导率。最终，该系列膜可以在高浓度甲醇作为燃料的直接甲醇燃料电池中实现优秀的性能。. 本项目突破了传统磺化聚芳醚酮质子交换膜材料非晶形态的概念，有据可依的给出了结晶性磺化聚芳醚酮质子交换膜的分子设计思路及具体制备过程，分析了分子结构-微观形貌-宏观性能的关系。同时发表了13篇SCI论文和4篇专利。