Synthesis and characterization of a novel poly(arylene ether sulfone) containing pendent imidazole groups for high temperature proton exchange membranes
作者:Jing Wang、Jifu Zheng、Zhuo Zhao、Suobo Zhang
DOI:10.1039/c2jm34417c
日期:——
A series of poly(arylene ether sulfone) containing pendent imidazole groups (PSf-Im-x) have been successfully synthesized based on a novel monomer 2,2′-bis-(2-methyl-imidazol-1-yl-methyl)-biphenyl-4,4′-diol (MIPO). The pendent imidazole groups along the polymer chain were expected to provide functional sites for the acid–base interaction with the doping phosphoric acid (PA) when they are used as polymer electrolyte membranes for high temperature fuel cell applications. The PA content of the linear PSf-Im-x membranes is about 172.3–235.8% in 85 wt% H3PO4 at room temperature. The volume swelling of these membranes is 114.4–194.0%, lower than that of polybenzimidazole (PBI) with similar PA content. The proton conductivities of the membranes are 0.021–0.053 S cm−1 at 140 °C under absolutely dehydrated state. The low volume swelling and good proton conductivity may be attributed to the “side-chain-type” structures of pendent imidazole groups, which facilitate ion transport. To obtain higher acid doping while maintaining mechanical properties, cross-linked membranes were prepared by the reaction of the imidazole group of the polymer and p-xylene dichloride. The PA content of the membranes with 20% cross-linking is 313.2% in 85 wt% H3PO4 at 80 °C. The stress at breaking and the proton conductivity of the membrane is 3.2 MPa at room temperature and 0.063 S cm−1 at 140 °C in an absolutely dehydrated state.
基于新型单体2,2'-双-(2-甲基-咪唑-1-基-甲基)-,成功合成了一系列含有咪唑侧基的聚亚芳基醚砜(PSf-Im-x)。联苯-4,4′-二醇(MIPO)。当它们用作高温燃料电池应用的聚合物电解质膜时,沿着聚合物链的悬挂咪唑基团有望为与掺杂磷酸(PA)的酸碱相互作用提供功能位点。室温下,在 85 wt% H3PO4 中,线性 PSf-Im-x 膜的 PA 含量约为 172.3-235.8%。这些膜的体积膨胀率为114.4-194.0%,低于具有相似PA含量的聚苯并咪唑(PBI)。在140 ℃、绝对脱水状态下,膜的质子电导率为0.021-0.053 S cm−1。低体积膨胀和良好的质子传导性可能归因于悬挂咪唑基团的“侧链型”结构,这有利于离子传输。为了在保持机械性能的同时获得更高的酸掺杂,通过聚合物的咪唑基团与对二甲苯二氯的反应制备了交联膜。 80°C、85 wt% H3PO4 中,20% 交联的膜的 PA 含量为 313.2%。在绝对脱水状态下,膜的断裂应力和质子电导率在室温下为3.2 MPa,在140 ℃下为0.063 S cm−1。