磺化聚芳醚酮砜/聚吡咯复合型直接甲醇燃料电池用质子交换膜的制备与性能研究

以高磺化度的磺化聚芳醚酮砜(SPAEKS)和吡咯(Py)为原料,通过原位聚合的方法制备了含有不同吡咯含量的SPAEKS/PPy复合膜.红外谱图表明SPAEKS聚合物中的磺酸基团与聚吡咯(PPy)中的亚氨基基团之间形成了强烈的相互作用.扫描电镜照片显示PPy能够均匀地分散在SPAEKS聚合物基体中,没有发生团聚现象.通过对复合膜的性能测试发现PPy的引入提高了复合膜的热稳定性,降低了复合膜的吸水率,改善了其水溶胀性.同时膜中水的脱附系数下降,提高了膜的保水能力.SPAEKS/PPy-3复合膜的甲醇渗透系数达到了1.18×10-7cm2/s,明显低于纯SPAEKS膜的8.52×10-7cm2/s,而其质子传导率虽有所降低,但在25℃和80℃仍然分别达到了0.039S/cm和0.061S/cm,能够满足质子交换膜对质子传导率的要求.研究结果表明,聚吡咯与SPAEKS中磺酸基的摩尔比为0.99的复合膜有望在直接甲醇燃料电池中得到应用.

PREPARATION AND PROPERTIES OF SULFONATED POLY(ARYLE ETHER KETONE SULFONE)S/POLYPYRROLE COMPOSITE MEMBRANES FOR DIRECT METHANOL FUEL CELLS

In order to meet the requirement of proton exchange membranes in direct methanol fuel cells (DMFCs),sulfonated poly(aryle ether ketone sulfone)/polypyrrole (SPAEKS/PPy) composite membranes with different contents of PPy were prepared in chemical in situ polymerization by means of ion-dipole interaction between the sulfonate groups of SPAEKS and imino groups of polypyrrole.The incorporation of polypyrrole particles into the clusters, which was the transport pathway,could change the morphology of the SPAEKS matrix.FTIR spectra suggested that the sulfonic acid groups on the copolymer backbone strongly interacted with amonium groups of PPy.SEM pictures showed that the PPy particles were uniformly distributed not only in regions near the surface but also in the internal space of the SPAEKS membranes matrix.The composite membranes showed good thermal stability,low water uptake,low swelling ratio both at length and thickness and relatively high proton conductive capability.The methanol diffusion coefficient (1.18×10^-7 cm²/s) of SPAEKS/PPy-3 composite membranes is much lower than that of pure SPAEKS membranes (8.52×10^-7cm²/s).At the same time,the selectivity increased with increasing the molar ratio between PPy and the sulfonate groups,meaning that the composite membranes have more impact on the reduction of methanol diffusion coefficient than that on proton conductivity.The selectivity of SPAEKS/PPy-3 composite membranes is much higher than that of pure SPAEKS membranes and other composite membranes,which suggests that the composite membranes with 0.99 molar ratio between PPy and the sulfonate groups of SPAEKS are promising as proton exchange membranes for DMFC applications.