Studies on Sulfonic Acid Functionalized Hollow Silica Spheres/Nafion® Composite Proton Exchange Membranes

In this work, sulfonic acid functionalized hollow silica spheres (SAFHSS)/Nafion (R) composite membranes were prepared by a recasting procedure. The influences of temperature on water uptake, swelling degree, and proton conductivity of the composite membranes were studied. In comparison with the pure recast Nafion (R) membrane, it was found that water uptake of composite membranes increased with increasing SAFHSS loading at all temperature studied. The swelling degree of SAFHSS/Nafion (R) composite membranes with 10 similar to 15 wt % SAFHSS loading was lower than that of the pure recast Nafion (R) at all temperatures in the study. The proton conductivity of SAFHSS/Nafion (R) composite membranes was constantly higher, than that of the pure recast Nafion (R) at all temperatures (50 similar to 130 degrees C). In a range from 50 to 130 degrees C, the highest conductivity of composite membranes was obtained when 10 wt % SAFHSS was loaded. The maximum conductivity reached 0.1 S cm(-1) at 100% relative humidity and 100 degrees C, even the temperature reached to 130 degrees C, the conductivity of the composite membranes with 10 wt % SAFHSS was still as high as 4.4 x 10(-2) S cm(-1) at 100% relative humidity, whereas the conductivity of the pure recast Nafion (R) was only 2.2 x 10(-3) S cm(-1). (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2647-2655, 2009