Study of Hybrid Membranes with Sulfonated-organomodified Fillers. Systems Based on Sulfonated-phenyl SBA-15

摘要

SBA-15 mesoporous material has been organo-modified by the incorporation of phenyl groups through covalent bond formation by a simple silylation reaction. In a second step, the anchored phenyl groups have been sulfonated so as to convert the mesoporous material into a proton conductor. Once modified, the solid was incorporated to two different polymers for membrane preparation: Nafion and sulfonated hydrogenated butadiene-styrene block copolymer (sHSBS) being the solid proportion in the mixture of 10 wt%. The cross sections of hybrid membranes were observed using scanning electron microscopy (SEM) showing a good dispersion of the filler into the polymer matrix; thermal stability was studied by thermogravimetry (TGA) and the results indicate that the loss of the ionic groups always takes place at higher temperatures than that of fuel cell working; proton conductivity was determined by means of electrochemical impedance spectroscopy (EIS) giving values that remain in the order of 10(-2) S.cm(-1); methanol permeabilities of the experimental membranes are more than one order of magnitude lower than Nafion; the incorporation of sulfonated-phenyl SBA-15 led to an improvement of single cell performance.