High-temperature proton exchange membrane with dual proton transfer; It) channels by incorporating phosphonic acid functionalized siloxane into poly (2,6-dimethy1-1,4-phenyleneoxide) (PPO)

A series of high-temperature proton exchange membranes were prepared by incorporating phosphonic acid functionalized siloxane synthesized from Amino Trimethylene Phosphonic Acid (ATMP) and 3-Aminopropyltriethoxysilane (APTES) into cross-linked 1-Methylimidazole-functionalized poly(2,6-dimethyl-1,4-phenyleneoxide) (PPO) backbone. The structural characteristics of membranes were investigated using FT-IR, H-1 NMR and XRD, indicating that ATMP and backbones of membranes were successfully immobilized into cross linking Si-O-Si networks formed by hydrolysis-polycondensation of APTES. The resultant membranes named as HTM-X exhibited superior oxidative resistance, mechanical properties and dimensional stability, even the thermal stability was up to 210 degrees C. The proton conductivities of membranes were also measured under different temperature. The result showed that HTM-15 membrane, whose content of phosphonic acid functionalized siloxane was 15 wt%, possessed the highest proton conductivity of 8.48 x 10(-2)S cm(-1) at 160 degrees C and low relative humidity (5%) with the contribution of dual proton transfer channels of acid-base pairs and continuous hydrogen bond networks. Therefore, this novel membrane acts as a potential candidate for proton exchange membranes operating at elevated temperature.