硅氧烷交联的咪唑基团功能化聚苯醚/聚四氟乙烯耐高温质子交换膜

Siloxane Crosslinked Imidazolium PPO/PTFE Membranes for High Temperature Proton Exchange Membranes

以聚苯醚(PPO)为基体材料,通过溴甲基化及咪唑基团功能化,与聚四氟乙烯(PTFE)复合、硅氧烷基团水解交联及磷酸掺杂,制备了兼具高磷酸掺杂含量、高质子电导率和良好机械性能的高温质子交换膜材料.以甲基咪唑(MeIm)和咪唑基硅氧烷化合物(Si Im)为功能化试剂(其中咪唑基团提供了磷酸作用位点,同时Si Im中的硅氧烷基团水解后得到Si—O—Si交联网络结构),提高了膜材料的机械稳定性.与PTFE的复合进一步增强了膜材料的机械强度.结果表明,复合膜具有较高的电导率和一定的机械强度.当磷酸掺杂质量分数为242. 5%时,PPO-50%Si Im-50%MeIm/PTFE复合膜在160℃不加湿条件下的电导率为0. 09S/cm,室温下的断裂拉伸强度为3. 6 MPa.

Based on poly(2,6-dimethyl-1,4-phenylene oxide)(PPO),novel high temperature proton exchange membranes were prepared with high phosphoric acid content,superior proton conductivity and excellent mechanical properties. Both methylimidazole(MeIm) and triethoxysilylpropyldihydroimidazole(SiIm)were used as functional reagents to graft the imidazolium groups onto the PPO polymer,in which the imidazolium group provided the phosphoric acid interaction sites. Meanwhile crosslinking of the modified PPO was achieved by forming a crosslinked silane network via the hydrolysis reaction of Si Im in an acidmedium.Moreover,porous poly(tetrafluoroethylene)(PTFE) was used as the membrane matrix toenhance the dimensional stabilities and mechanical strength of the fabricated membranes. Physicochemical properties of composite membranes with various crosslinking degrees were investigated accordingly. The results showed that the PPO-SiIm-MeIm/PTFE composite membranes possessed dense structure, superior thermal stability,improved chemical stability, high conductivity and suitable mechanical strength simultaneously. As an example,the PPO-50% SiIm-50% Me Im/PTFE membrane with a phosphoric acid doping content of 242. 5%exhibited a conductivity of 0. 09 S/cm at 160 ℃ under no humidification conditions,and a tensile strength of3. 6 MPa at room temperature. The results indicate that PPO-x% Si Im-y% MeIm/PTFE membranes have the potential to be used as HT-PEMs.