Phosphonic acid functionalized siloxane crosslinked with 3-glycidoxyproyltrimethoxysilane grafted polybenzimidazole high temperature proton exchange membranes

Phosphonic acid functionalized siloxane crosslinked with 3-glycidoxypropyltrimethoxysilane (GPTMS) grafted polybenzimidazole (PBI) membranes are prepared by sol-gel process. The structure of the membranes is characterized by Fourier-transform infrared spectroscopy and X-ray diffraction spectroscopy. SEM images of the membranes show that the membranes are homogeneous and compact. The crosslinked membranes exhibit excellent thermal stability, chemical stability and mechanical property. The proton conductivity of the crosslinked membranes increases by an order of magnitude over range of 20 degrees C to 160 degrees C under anhydrous condition, which can reach 3.15 x 10(-2) Scm(-1) at 160 degrees C under anhydrous condition. The activation energy of proton conductivity for membranes decreases with increase of PBI, because the formation of hydrogen bond network between the phosphonic acid and the imidazole ring can enhance the continuity of hydrogen bond in the membrane. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44818.