National University of Singapore Graduate School for Integrative Science and Engineering, 28 Medical Drive, 117456, Singapore.
J Phys Chem B. 2012 Jun 7;116(22):6416-24. doi: 10.1021/jp2081353. Epub 2012 May 24.
This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.
本文描述了离子对增强型半互穿聚合物网络（SIPN）作为质子交换膜（PEM）在直接甲醇燃料电池（DMFC）中的合成。具体而言，线性聚合物质子源磺化聚（2,6-二甲基-1,4-苯撑氧化物）（SPPO）通过乙二胺（EDA）共价交联固定在溴化聚（2,6-二甲基-1,4-苯撑氧化物）（BPPO）网络中。SPPO 在 SIPN 网络中的固定不仅通过通常的机械互锁方式实现，而且还通过 SPPO 的磺酸基团与 BPPO 与 EDA 的交联反应过程中形成的胺部分之间的离子对形成来实现。通过离子对相互作用，SPPO 聚合物在 BPPO 网络中的固定更加有效，导致膜中磺酸簇分布更加均匀。含亲水性胺的交联也弥补了部分由离子对形成引起的质子传导率降低。因此，所制备的 SIPN 膜具有良好的质子传导率、低甲醇渗透率、良好的机械性能和尺寸稳定性。因此，基于 PPO 的 SIPN 膜能够提供比 Nafion 更高的最大功率密度，证明了 SIPN 结构在 PEM 设计中的潜力。
