Electrochemical Studies of Surface-Modified Glass Bead/Nafion Composites

Abstract

In the past decade, electrochemists have begun modifying electrode surfaces with polymer composites. Each of those composites had advantages over the standard polymer modified electrode. Usually, the major advantage is increased sensitivity. However, years of chromatographic research have proven that tailoring the surface of glass beads can increase the selectivity of a system. The same principle should be applicable to polymer film composites. This research is based upon making glass bead/ion exchange polymer composites with unique interfaces that alter the selectivity of redox species on the basis of physical and chemical characteristics. This is accomplished by modifying the surface of glass beads with organosilanes of varying chain lengths and functional groups. The significance of this research lies in its ability to alter the selectivity of polymer modified electrodes. A surface-modified glass bead/Nafion composite was designed that excludes Ru(bpy)3 2+ from the film. The surface-modified glass bead/Nafion composites were able to alter electrochemical flux for hydroquinone, methylviologen, and Ru(bpy)3 2+. Composites have no significant effects on the electrochemical flux of Fe3+.

Electrochemical Effects of Surface-Modified Glass Microspheres in Polyvinylpyridine and Polystyrene Sulfonate Composite Electrodes

“…This is consistent with previous experiments on glass bead/Nafion composites, which showed that there was no measurable effect on the electrochemical flux of Fe 3+ due to the formation of any of the glass bead/Nafion composites. 11 This similarity is expected because Fe 3+ is a small, hydrophilic inorganic ion which diffuses through both PSS and Nafion (D app ) 2.9 × 10 -7 cm 2 /s 22 ) rapidly, so small changes in the interfacial region have little effect on the electrochemical flux.…”

“…Earlier work in organosilane-modified glass bead/Nafion composites showed that the selectivity of the electrode could be altered by changing the functional end group on the organosilane. 11 This work examines the selectivity of organosilane-modified glass microsphere/PVP and PSS composites and the role of the polymer in the formation of these unique interfaces. Electrochemical selectivity is more complicated than chromatographic selectivity.…”

“…7 Recently, it has been shown that composite films can also alter the electrochemical selectivity of the electrode. 11 Previous studies in our laboratory have examined composites of Nafion and glass microspheres that were modified with commercially available organosilanes of different functional groups, including amino, chloro, methacryloxy, and phenyl functional groups. 11 The silanol groups on the surface of the glass bead react with the organosilanes to form stable siloxane bonds.…”

“…11 Previous studies in our laboratory have examined composites of Nafion and glass microspheres that were modified with commercially available organosilanes of different functional groups, including amino, chloro, methacryloxy, and phenyl functional groups. 11 The silanol groups on the surface of the glass bead react with the organosilanes to form stable siloxane bonds. The process is relatively simple and has been used by chromatographic researchers for decades.…”

“…Previous studies examined the role of the functional group of the organosilane in the formation of a unique interface 11 but not the role of Nafion in the formation of the unique interface. Nafion is a popular cation exchange polymer.…”