Proton conductive inorganic–organic hybrid membranes prepared from 3-aminopropyltriethoxysilane and phosphoric acid by the sol–gel method

Abstract

Proton conductive inorganic–organic hybrid membranes with acid–base pairs have been prepared from 3-aminopropyltriethoxysilane and phosphoric acid by the sol–gel method. The self-standing membranes obtained are represented as poly(3-aminopropylsilsesquioxane)-H 3PO 4 (PAPS–H 3PO 4) membranes. Infrared absorption spectra of the PAPS–H 3PO 4 films showed that amino groups of PAPS were protonated by phosphoric acid, indicating the formation of acid–base pairs. X-ray diffraction patterns of the PAPS–H 3PO 4 membranes showed diffraction peaks attributed to hexagonal structure, which is probably formed by stacking of rodlike polysiloxane with the acid–base pairs extruded outside. The conductivities of the PAPS–H 3PO 4 membranes with a molar ratio of H 3PO 4/APTES = 1.0 was 4 × 10 − 4 S cm − 1 at 150 °C under dry condition.