基于巯基改性磺化海泡石与聚(2,5-苯并咪唑)原位复合的宽温域用质子交换膜

天然海泡石经微波辅助酸活化和巯基偶联剂改性得到磺化海泡石,然后原位合成制备燃料电池宽温域用聚(2,5-苯并咪唑)/磺化海泡石(ABPBI/S-Sep)复合质子交换膜。研究了海泡石改性前后结构变化,以及S-Sep粒子的加入对复合膜的微观形貌、结构、力学性能、吸水固酸能力以及高、低温下质子传导性能的影响。研究发现,海泡石粒子经微波辅助酸活化处理后产生了解纤维化,磺化改性提高了其与聚合物相容性;S-Sep纤维状粒子均匀分散在ABPBI基体中可诱导聚合物分子链取向排列,从而提高复合膜的力学性能,其特有的纳米通道结构及高比表面积显著提高了复合膜的吸水率和固酸能力。在相似磷酸(PA)掺杂水平下,复合膜在40～180℃宽温域下的质子传导率和峰值功率密度均高于ABPBI膜,并且磷酸掺杂水平为1.85的复合膜在90℃以下,60%和98%RH时质子传导性能以及80℃、0%RH时单电池性能均与Nafion 212相当,表明低磷酸掺杂水平下的S-Sep改性ABPBI复合膜具备从低温到高温且不控制湿度的宽温域使用优势,可拓展基于PA掺杂聚苯并咪唑类膜材料的使用温度范围。

Proton Exchange Membrane Based on In-Situ Synthesis of Poly(2,5-benzimidazole)and Mercapto-Functionalized Sulfonated Sepiolite for Application in a Wide Temperature Range

A new type of poly(2,5-benzimidazole)/sulfonated sepiolite(ABPBI/S-Sep)composite proton exchange membrane for fuel cell application in a wide temperature range was prepared by in-situ synthesis.The natural sepiolite(Sep)was firstly treated by microwave-assisted acid activation and then surface modified by mercapto coupling agent then oxidized to obtain sulfonated sepiolite(S-Sep).The changes of structure and properties of Sep particles before and after modification,and the influence of the incorporation of SSep particles on the micro-morphology,structure,mechanical properties,water and acid absorbabilities as well as proton conductivity of composite membranes at a wide temperatures range,were investigated.The results show that,the Sep particles were treated by microwave-assisted acid activation to achieve the defibration effect,and the sulfonation modification improves the compatibility with the polymer.The S-Sep fiberparticles are uniformly dispersed in the ABPBI polymer matrix,which can induce the orientation alignment of the polymer chains along with S-Sep fibers thereby exhibit the crystallization tendency,resulting in the improved mechanical properties.Compared with the pure ABPBI membrane,the S-Sep particles with an unique nano-channel structure and high specific surface area drive in the significant improvement of water and acid absorb abilities of the composite membranes.Under the similar phosphoric acid doping level,the proton conductivities and peak power densities of the composite membranes are much higher than those of the pristine ABPBI membrane at a wide temperatures range of 40~180℃.It is notably that the proton conductivities at 90℃,60% and 98% RH and peak power density at 80℃,0%RH of the ABPBI/S-Sep composite membrane with the doping level of 1.85can be comparable to those of Nafion 212,respectively,indicating that the SSep modified ABPBI composite membrane with a low phosphoric acid doping level has the superiority of applications in a wide temperature range from low to high temperatures without humidity control,therefore can expand the operating temperature range of phosphoric acid doped polybenzimidazoles membranes.