Date of Award
Doctor of Philosophy (PhD)
Electrode activity can be controlled by coating the electrode surface with aptly designed polymeric redox compounds. A short review of the literature concerning chemically modified electrodes (CME's) is presented. Although many techniques for producing CME's have been reported, little attention has been paid to the role played by the polymer matrix in controlling electroactivity. In this work, ferrocene functional groups have been incorporated into a series of polymers with varying glass transitions and polarity and the electroactivity of the ferrocene moieties has been evaluated by cyclic voltammetry. General methods are described for the synthesis and characterization of chloromethylated polymers. The polymers include: poly(vinylbenzyl chloride), a series of vinylbenzyl chloride - methyl methacrylate copolymers, a series of vinylbenzyl chloride - 2 -ethoxyethyl methacrylate copolymers, and poly(arylether sulfones) chloromethylated to varying extents. Phase transfer techniques for immobilizing ferrocene carboxylate are detailed. Polymers with loadings ranging from 1.19 to 2.03 meq ferrocene/g are described. Hydrophilic poly(ferrocenylmethyl arylether sulfone) can be prepared by reaction of a trialkylamine with partially derivatized poly(arylether sulfones) to introduce 2 - 33 mole % quaternary ammonium halide functional groups. Cyclic voltammetry is used to ascertain the parameters that affect the electroactivity of the ferrocene redox sites both in coated thin films and in solution. A wide range of electrochemical properties can be observed by varying the following parameters: film thickness, nature of the polymer backbone, extent of functionalization, type of solvent, and supporting electrolyte. The film resistance is a function of the rigidity of the polymer backbone, the extent of ferrocene loading, and the extent of quaternized functional groups attached to the support. The variable resistance is shown to be a consequence of slow solvent and counterion diffusion through the polymer matrix. The percent of electroactive ferrocene sites relative to the support loading (efficiency) is calculated. The efficiency depends upon at least two factors, spacing between redox sites and the extent of site solvation. The impact of partial quaternization of the polymer support is phenomenal; the efficiency of poly(ferrocenylmethyl arylether sulfone) increases from 25% to 65% upon introduction of 2 mole % quaternary ammonium halides.
Sittattrakul, Amnard, "Specific Polymer Supports for Electroactive Reagents (Electrodes)." (1985). LSU Historical Dissertations and Theses. 4161.