Chemistry
Triazole bearing sol-gel membranes as water free proton exchange membranes for hydrogen fuel cells
Abstract
Water free, proton conducting, free-standing membranes have been synthesized by incorporating triazole containing tetracyclosiloxanes into a PEG-TEOS based sol-gel matrix. The absence of any unbound PEG or cyclic siloxane was confirmed by 1H-NMR and the chemical structure of the membranes was corroborated by FTIR spectroscopy. TGA analysis indicated that the membranes are stable up to 250 °C and DSC analysis showed complete suppression of PEG crystallization after incorporation of the triazole containing cyclosiloxanes. The crosslinked membranes showed proton conductivities higher or comparable to those observed for the liquid, polysiloxane analog, notwithstanding the lower charge carrier density of the sol-gel membranes and the pronounced improvement in mechanical strength compared to the linear polysiloxanes. These results suggest that incorporation of small proton conducting molecules into an inert sol-gel matrix may reduce the coupling between mechanical strength and ion transport ability, providing a new pathway for mechanically robust, water free, proton conductive membranes.
