测试介质对纳米CeO_2改性SPEEK膜质子电导率的影响

采用纳米氧化铈(CeO2)改性磺化度48.3%的磺化聚醚醚酮(SPEEK),通过溶液浇铸法制备用于直接甲醇燃料电池的质子交换膜.在两种介质中测试改性膜的电导率均随温度的升高而增大,与未改性膜相比却大小正好相反:在1 mol/L以盐酸溶液为电解液的测试介质中,改性膜的电导率是未改性膜的15倍,在水蒸气测试介质中,却仅为40%.红外光谱分析表明,CeO2中的铈原子与—SO3H基团中的氧原子发生配位作用.X射线衍射仪(XRD)分析可见,当复合膜浸入1 mol/L盐酸4 h前后,纳米CeO2的晶体结构未见明显变化,表明所发生的配位作用仅处于CeO2和SPEEK两个固相界面上.扫描电子显微镜(SEM)观察改性膜和未改性膜均无网络结构和微相分离,质子在膜内通过—SO3H基团之间的跃迁传导,酸溶液介质远比水蒸气有利于质子在纳米CeO2改性SPEEK膜内磺酸基团之间的跃迁.     

溶剂对溶液法制备的SPEEK质子交换膜性能的影响

本文在聚醚醚酮(PEEK)磺化反应制备相同磺化度的磺化聚醚醚酮(SPEEK)基础上,采用不同的溶剂通过溶液法制备一系列SPEEK质子交换膜,采取交流阻抗法、扩散池法和溶胀法分别评价其导质子能力、阻醇性能和溶液稳定性,探讨溶剂种类对SPEEK质子交换膜性能的影响规律.试验结果表明溶剂对所制备膜的导质子能力和阻醇性能影响依赖于溶剂分子与SPEEK中磺酸基团的相互作用,若存在越强作用,膜的导质子能力越弱,而阻醇性能越高.此外,溶剂种类对膜的吸水溶胀性能存在较小的影响,对膜表面的微孔形态存在明显的影响,并与膜的导质子能力及阻醇性能存在对应关系.综合比较不同溶剂制备膜的导质子能力、阻醇性能和吸水溶胀性能,DMAc是优于DMF和DMSo的制膜溶剂.     

Characterization of SPEEK/Y2O3 proton exchange membrane treated with high magnetic field

The membranes of sulfonated poly(etheretherketone) of 48.3% sulfonation degree doped with Y2O3 were prepared, and then treated with parallel high magnetic field of 6 and 12 T at 120 oC for 4 h, respectively. The small-angle X-ray scattering revealed that the struc- ture of the composite membranes would be changed by high magnetic field treatment. The cross-section morphology of the composite membranes by a scanning electron microscope showed that the Y2O3 could be dispersed evenly in the composite membranes which were relatively smooth and compact but formed small conglomeration with increasing Y2O3 content and treating high magnetic field. The water uptake of membranes would be reduced with Y2O3 content increasing, but not be modified by the treatment of high magnetic field. The proton conductivity of membranes would be increased with temperature rising from 20 to 60 oC, and improved under high magnetic field, which could all exceed 10-2 S/cm at 75% relative humidity, but decrease with doping content of Y2O3 from 2 wt.% to 8 wt.%. The methanol permeability of the composite membranes would be decreased with Y2O3 content increasing and slightly reduced after high magnetic field treatment.